World boxing champion Kell Brook, from Sheffield, is in hospital in Tenerife after being stabbed in the leg while on holiday.
Brook's condition is described as "stable" by his promoters Matchroom, but a spokeswoman for Spain's Guardia Civil said he had "lost a lot of blood".
She said on Thursday: "This morning a 28-year-old British man was stabbed at Golf del Sur in San Miguel de Abona. He was stabbed in the left leg and is hospitalised. He lost a lot of blood.
Brook savours victory in his IBF Welterweight World Championship fight
"There are no arrests at this time and the Guardia Civil are investigating."
Brook won the IBF welterweight title with a majority decision win over American Shawn Porter in California last month.
The fighter is being lined up for a fight against Amir Khan, with some reports suggesting the fight was due to be announced next week.
It is the second time Brook has been stabbed, after sustaining injuries in an incident in his home city in 2007.
Brook's win over Porter stretched his unbeaten professional record to 33 fights and marked him out as one of the leading names in his division.
The fight ended a period of frustration for Brook, who had seen three prospective title fights against former champion Devon Alexander fall through in the 18 months prior to his win over Porter.