Lionel Messi's bid to surpass Gerd Müller's record of 85 goals in a calendar year is in jeopardy after the Barcelona attacker was carried off on a stretcher in their Champions League match with Benfica.
Messi arrived as a 58th minute substitute in the goalless draw but collided with the Portuguese side's goalkeeper Artur, injuring his knee in the process.
Barça announced Messi has "a bruise on the outside of his left knee" and will undergo further tests to determine the extent of his injury.
The 24-year-old has scored 84 goals for Barça and Argentina this year. He has four matches left this year to overhaul Müller's tally - La Liga games against Real Betis, Atletico Madrid and Real Valladolid, as well as a Copa del Rey tie with Córdoba.
Barcelona had already qualified as winners of Group G prior to their final fixture on Wednesday night, having lost just one of their six matches against Celtic last month.
Lionel Messi Injured
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Barcelona's Argentinian forward Lionel Messi leaves the pitch on a stretcher after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / JOSEP LAGO (Photo credit should read JOSEP LAGO/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi reacts after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi leaves the pitch on a stretcher after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE,LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(04 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona reacts on the pitch after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(05 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of Barcelona reacts after being fouled during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at the Camp Nou stadium on December 5, 2012 in Barcelona, Spain. Messi was taken off the pitch. (Photo by Jasper Juinen/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(06 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona reacts on the pitch after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(07 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of Barcelona lines up a free kick during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at the Camp Nou stadium on December 5, 2012 in Barcelona, Spain. Messi was taken off the pitch. (Photo by Jasper Juinen/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(08 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of Barcelona reacts after being fouled during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at the Camp Nou stadium on December 5, 2012 in Barcelona, Spain. Messi was taken off the pitch. (Photo by Jasper Juinen/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi leaves the pitch on a stretcher after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / JOSEP LAGO (Photo credit should read JOSEP LAGO/AFP/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(10 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona reacts on the pitch after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi reacts after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi (L) vies with Benfica's Brazilian goalkeeper Artur Moraes during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi (L) is injured while vying with Benfica's Brazilian goalkeeper Artur Moraes during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi leaves the pitch on a stretcher after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / JOSEP LAGO (Photo credit should read JOSEP LAGO/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi lies on the pitch after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi reacts after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(17 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi (L) of Barcelona injures himself while trying to score his record goal after passing by goalkeeper Artur of SL Benfica during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at the Camp Nou stadium on December 5, 2012 in Barcelona, Spain. Messi was taken off the pitch. (Photo by Jasper Juinen/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi leaves the pitch on a stretcher after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi leaves the pitch on a stretcher after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi lies on the pitch after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi (C) lies on the pitch after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / JOSEP LAGO (Photo credit should read JOSEP LAGO/AFP/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(22 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona leaves the pitch on a stretcher after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(23 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona is seen by the FC Barcelona doctor after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(24 of40)
BARCELONA, SPAIN - DECEMBER 05: FC Barcelona doctors run towards Lionel Messi of FC Barcelona as he reacts on the pitch after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(25 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona leaves the pitch on a stretcher after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(26 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona leaves the pitch on a stretcher after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(27 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of Barcelona reacts aftre being fouled during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at the Camp Nou stadium on December 5, 2012 in Barcelona, Spain. Messi was taken off the pitch. (Photo by Jasper Juinen/Getty Images) (credit:Getty Images)
FC Barcelona v SL Benfica - UEFA Champions League(28 of40)
BARCELONA, SPAIN - DECEMBER 05: Lionel Messi of FC Barcelona leaves the pitch on a stretcher after being injured during the UEFA Champions League Group G match between FC Barcelona and SL Benfica at Nou Camp on December 5, 2012 in Barcelona, Spain. (Photo by David Ramos/Getty Images) (credit:Getty Images)
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Barcelona's Argentinian forward Lionel Messi leaves the pitch on a stretcher after being injured during the UEFA Champions League football match FC Barcelona vs SL Benfica at the Camp Nou stadium in Barcelona on December 5, 2012. AFP PHOTO / LLUIS GENE (Photo credit should read LLUIS GENE/AFP/Getty Images) (credit:Getty Images)
Lionel Messi(30 of40)
FC Barcelona's Lionel Messi from Argentina is placed on a stretcher after suffering an injury during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi(31 of40)
FC Barcelona's Lionel Messi from Argentina is placed on a stretcher after suffering an injury during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi(32 of40)
FC Barcelona's Lionel Messi from Argentina lies on the pitch during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi(33 of40)
FC Barcelona's Lionel Messi from Argentina lies on the pitch during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi(34 of40)
FC Barcelona's Lionel Messi from Argentina reacts after suffering an injury during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi, Artur Moraes(35 of40)
FC Barcelona's Lionel Messi from Argentina duels for the ball against Benfica's goalkeeper Artur Moraes, from Brazil during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi(36 of40)
FC Barcelona's Lionel Messi, from Argentina, reacts after been injured during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi(37 of40)
FC Barcelona's Lionel Messi from Argentina reacts after he was injured during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi(38 of40)
FC Barcelona's Lionel Messi from Argentina reacts after suffering an injury during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi, Nemanja Matic(39 of40)
FC Barcelona's Lionel Messi from Argentina, left, duels for the ball against Benfica's Nemanja Matic from Serbia during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)
Lionel Messi, Nemanja Matic(40 of40)
FC Barcelona's Lionel Messi from Argentina vies for the ball against Benfica's Nemanja Matic from Serbia during a group G Champions League soccer match against Benfica at the Camp Nou stadium in Barcelona, Spain, Wednesday, Dec. 5, 2012. (AP Photo/Manu Fernandez) (credit:AP)