Boxer Dale Evans has spoken of his heartbreak following the death of opponent Mike Towell.
Towell, 25, died in hospital on Friday night following a televised bout with Evans in Glasgow the previous day.
Tributes have flooded in following the death of the father from Dundee.
Welsh boxer Evans told BBC Wales Sport: "I feel like I am responsible. I can't stop thinking about Mike and his poor family. All my thoughts are with them."
Evans, 24, said he never dreamt something like this would happen.
He added: "It has been awful. All I can think of is his two-year-old kid and his girlfriend and family who won't have him around any more.
"I feel like I am responsible because we are the ones punching each other - and this is something I have to live with now."
Evans also told the BBC the incident saw him consider retiring from the sport but that he would now like to win the British title in Towell's memory.
The welterweight, known as "Iron Mike Towell", was stretchered from the ring after a fifth-round loss to Evans in a televised bout at a St Andrew's Sporting Club event in Glasgow.
He was taken to Queen Elizabeth University Hospital, diagnosed with severe bleeding and swelling to his brain, and died shortly after 11pm on Friday, 12 hours after being taken off life support.
The boxer's family were at his bedside in his final hours and were joined by his manager, Tommy Gilmour, and St Andrew's Sporting Club owner Iain Wilson.
It later emerged Towell had cut short a training session after suffering a headache in the weeks before the fatal fight.
His partner Chloe Ross said he died "peacefully".
She wrote on Facebook: "My baby has lost his daddy. But he will be so, so proud of his dad in what he achieved."
An appeal set up by former world champion boxer Ricky Hatton to raise money for Ms Ross, and the couple's young son, Rocco, has surpassed its £20,000 target and has now raised more than £29,000.
The British Boxing Board of Control released its own statement on Monday afternoon which read: "The British Boxing Board of Control sends their condolences to the family of Mike Towell.
"The thoughts of all those involved in boxing in Great Britain are with them at this difficult time."
The BBBofC released a separate statement indicating its intention to investigate the circumstances surrounding Towell's death.
"The British Boxing Board of Control are in the process of gathering information from all relevant parties in relation to the contest which took place on the September 29, 2016 and will advise of further action by the stewards of the board at a later date," the other statement read.