Bolton Wanderers midfielder Fabrice Muamba remains "critically ill in intensive care", after having a cardiac arrest during his side's FA Cup quarter-final against Tottenham Hotspur.
The midfielder has been admitted to the Heart Attack Centre at the London Chest Hospital after collapsing at White Hart Lane. He received CPR and electric shock treatment from medics, as they tried to resuscitate him.
He was initially listed as being in a "stable condition", but Bolton released a statement stating his well-being had changed. They have also requested the public to respect his family's privacy.
He suddenly collapsed in the 41st minute in an off-the-ball incident and was treated for over five minutes on the pitch, to the distress of players and supporters.
Resuscitation was also being carried out as he was taken off the pitch.
Spurs and Bolton fans chanted his name in unison, whilst other supporters, saddened by the trauma, wept.
Referee Howard Webb took both sets of players off in light of Muamba's condition, and the game was called off.
Live broadcasters ESPN opted not to show the medical staff treat the 23-year-old out of respect to the procedure.
Commentating on ESPN, John Barnes said: "From the players' reaction on both sides it seemed that things were pretty serious."
Kevin Keegan added: "Jermain Defoe seemed absolutely distraught.
Wayne Rooney is just one of a host of footballers wishing Muamba well:
"The fans are in a state of shock. I've never seen anything like that on a football pitch before.
"Our hearts go out to his family."
Muamba was jogging towards his own half when he collapsed.
Bolton manager Owen Coyle ran on to the pitch to check on the status of his player as he received medical treatment, while players gathered and a defibrillator was used on the Zaire-born ex-Arsenal trainee.
Applause greeted the tannoy announcer's revelation the game had been abandoned, and Muamba's name again rang around White Hart Lane.
Ex-Manchester City and West Ham United midfielder Marc Vivien-Foe collapsed and died during a Confederations Cup match in 2003 for Cameroon in Nyon, France.
Motherwell's Phil O'Donnell also fell in a game against Dundee United in December 2007 and passed away.
Tottenham Hotspur's William Gallas reacts on the pitch after Bolton Wanderers' Fabrice Muamba collapses
(left-right) Tottenham Hotspur's Carlo Cudicini, Luka Modric and Louis Saha look concerned after Bolton Wanderers' Fabrice Muamba collapses on the pitch and is resusitated by medical staff
Tottenham Hotspur's Luka Modric (2nd left), Bolton Wanderers' Ivan Klasnic, referee Howard Webb and manager Bolton Wanderers' manager Owen Coyle look on after Fabrice Muamba collapses on the pitch
Tottenham Hotspur's Benoit Assou-Ekotto (left), William Gallas, Carlo Cudicini and manager Bolton Wanderers' manager Owen Coyle look on after Fabrice Muamba collapses on the pitch
Tottenham Hotspur's Jermain Defoe, Ryan Nelsen and Luka Modric react after Bolton Wanderers' Fabrice Muamba is carried off on a stretcher
Tottenham Hotspur's Jermain Defoe reacts on the pitch after Bolton Wanderers Fabrice Muamba collapses on the pitch
Players walk back into the tunnel after the game is abandoned after Bolton Wanderers Fabrice Muamba collapses on the pitch
The medical team tend to Bolton Wanderers' Fabrice Muamba as Ryo Miyaichi, Darren Pratley and Dedryck Boyata look on