Michael Zerafa has paid tribute to fellow Australian boxer Dwight Ritchie, who died after collapsing during their sparring session.
Zerafa says Ritchie, 27, suddenly stopped fighting during the sixth round of Saturday's session in Melbourne, took a few backward steps, held his chest and collapsed.
Paramedics tried unsuccessfully to revive Ritchie in the ring.
The father-of-three was due to return to the ring next month, having suffered only the second loss of his 21-fight career to Tim Tszyu - when they fought for the IBF Australasian super-welterweight title in August.
Zerafa was preparing for his rematch with Jeff Horn.
Zerafa told the Seven Network the last blow he landed was to Ritchie's chest and was "nothing out of the ordinary".
"No shots landed that were really different. Just something happened," he said.
Zerafa was full of praise for his good friend Ritchie.
"There are simply no words to describe how I am feeling right now," Zerafa wrote on exclusiveinsight.com, in an article published on Sunday.
"Dwight was one of the most humble people I have ever met.
"We had known each other since we were teenagers, when we were just starting out in the sport. And for the past 10 years, Dwight and I had been supporting each other inside, and outside of the ring.
"There had always been a professional and mutual respect between us.
"Yesterday, was an absolute tragedy, and as tough as it is right now for myself, I can only imagine how difficult the past 24 hours has been for Dwight's family.
"My heart bleeds for his three children and his beautiful partner. I have spoken to the family, and given my deepest condolences.
"The boxing community has lost a truly great person, and I have lost a mate.
"I appreciate all the messages of support that I have been receiving from family, friends, media and the boxing community.
"Dwight's passing is a further reminder why we can't take life for granted. Nothing in life is guaranteed...
"He taught me so much, not just as a boxer but as a person, and I will always be thankful for the lessons Dwight shared with me about life.
"Dwight, you will always be remembered. Rest in Peace mate."
Whether Zerafa's rematch with Horn in December goes ahead is still unclear.
Outpouring of grief from boxing community
Ritchie’s promoter, Jake Ellis, confirmed the tragic news of Ritchie’s death in a touching Facebook post on Saturday.
“It is with great sadness and shock to announce that the ‘Fighting Cowboy’ Dwight Ritchie sadly passed away today doing what he loved," he wrote.
"As Dwight’s promoter and friend it’s unbearable to accept the tragic news that’s just surfaced.
"Dwight will always be remembered by the boxing fraternity as one of the brightest talents in Australia whose fighting style embodied exactly how he lived."
Fellow fighters, commentators and various other boxing figures were left in shock by the 27-year-old’s death, with an outpouring of grief flooding social media.
Confirming the heartbreaking news that Australian boxer Dwight Ritchie has today passed away after a freak training accident. He was 27. RIP Cowboy #DwightRitchie 💔— Ben Damon (@ben_damon) November 9, 2019
Today we lost one of our own 😔— Luke Jackson (@LukeJackson) November 9, 2019
I remember having my professional debut on Dwight’s card. Sending my love to his family, loved ones and the whole of boxing Australia 💔
RIP Dwight Ritchie 🙏🏼 pic.twitter.com/dAzV6cAF2T
I haven't got anything poetic to add around Dwight Ritchie's passing. Heartbreaking consequence of an extremely dangerous sport. Truly tragic story— Corbin Middlemas (@CorbinMiddlemas) November 9, 2019