Irish fighter Lee Reeves was taken to hospital after being knocked out in the 10th-round of his fight against Gary Cully in Dublin on Saturday.
Reeves, 31, was knocked down twice in the round. He did not get back to his feet the second time and was carried off on a stretcher and rushed to hospital.
The fight was on the Pierce O'Leary vs. Mark Chamberlain undercard at the 3Arena in the Irish capital.
Queensberry promoter Frank Warren said in a statement: "All our thoughts and prayers are with Lee Reeves and his family at this time as he remains in hospital.
"Everyone at Queensberry is thinking of him and we're in constant contact with his team regarding his condition as we hope for positive news."
Cully, 30, also shared his well-wishes after the fight.
"My prayers and thoughts are with Lee Reeves, hopefully he's okay," Cully said.
"He came in there as a big underdog after fighting relatively at a lower level up until now, but he really showed that he can operate at a higher level. Huge credit to him."