Michael Conlan was said to be "conscious and stable" after being taken to hospital following his brutal final-round knockout to Leigh Wood.
Conlan was reportedly ahead on all three judges' scorecards when Wood sent the Belfast challenger through the ropes.
There was concern for the 30-year-old who required medical assistance at ringside before being stretchered out of the arena and taken to hospital.
Read more: Concern for Michael Conlan after final round knockout in Nottingham
Conlan had been in control of the WBA world featherweight title clash, dropping Wood in the first round and dominating and early stages of the fight.
But Wood powered back and dropped his opponent in the 11th round before delivering a brutal stoppage which left Conlan out cold.
The Belfast boxer fell out of the ring and was immediately tended to by paramedics but was later reported to be conscious before being put in an ambulance where he was in a stable condition.
Matchroom CEO Frank Smith said: "Michael Conlan arrived at hospital, conscious and stable."
Steve Bunce, reporting for the BBC, had earlier said: "He's not fully unconscious. He's talking and looking up to the crowd."
Matchroom chief Eddie Hearn later confirmed Conlan was "sitting up and talking" as he awaited a CT scan.
It was an ugly end to what had been a pulsating world title fight in Nottingham.
Wood - who was making the first defence of the title he won last year - told DAZN: "I just want to say thank you for all the fans. All the Irish travelling fans.
"I hope Michael is okay. I can't really celebrate until I find out he is okay. My thoughts are with him at the minute.
"He is so tough. I hit him with everything. I kept going to the last bell.
"But I am just thinking about Mick at the minute. It was a bad knockout. I can' get him out of my head. I hope he's okay."
Matchroom promoter Eddie Hearn added: "We should be celebrating one of the biggest comebacks we have seen, but we are just praying for Michael Conlan.
"It was just the most brave, courageous fightback from Leigh Wood. he got knocked down in he first round and it was a master class from Michael Conlan for the early to mid rounds.
"For Leigh to win that by knockout is one of the best comebacks we have seen. But our thoughts are with Michael Conlan who fought a master class performance tonight.
"Conlan was winning the fight and Leigh Wood had to knock him out to retain his title, and he did it. We would love to celebrate but our thoughts are with Michael Conlan right now."
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