Michael Conlan's bid to become world champion ended with a devastating 12th-round knockout on Saturday night.
The Belfast challenger slumped through the ropes after being stopped by Leigh Wood who defended his WBA world featherweight title in Nottingham.
It was a brutal end to a thrilling contest at the Motorpoint Arena.
Read more: Michael Conlan vs Leigh Wood LIVE fight updates from Nottingham
Conlan had Wood down in the opening round and wobbled the champion in the second.
The 30-year-old had been dictating most of the fight but Wood grew into the contest in the later rounds.
Conlan was judged to have touched the canvas in the 11th despite his corner claiming it was a slip.
That appeared to give Wood confidence heading into the final round, and the champion landed a heavy shot that folded Conlan on the ropes before the Belfast challenger fell through the other side.
It was a heartbreaking end to a thrilling world title fight in front of 10,000 fans.
Conlan required medical assistance at ringside, with Wood's muted celebrations highlighting the concern at ringside.
Wood 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."
Conlan was taken to hospital after the fight but was said to be conscious as he left the arena and had waved to fans.
Matchroom CEO Frank Smith later added: "Michael Conlan arrived at hospital conscious and stable."
The Belfast fighter was reportedly ahead on all three judges' scorecards going into the final round before he was stopped.
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