Nick Blackwell is in hospital after suffering a bleed on the brain following his British middleweight title defeat by Chris Eubank Jr in London on Saturday.
The referee stopped the fight in round 10 on the advice of the doctor, who said Blackwell was unable to continue because of swelling over his left eye.
The beaten champion was later taken from the ring on a stretcher.
Blackwell, 25, has been placed in an induced coma.