Boxer Patrick Day has died at the age of 27 after sustaining head injuries in his fight in Chicago on Saturday, promoter Lou DiBella has confirmed.
Day was knocked out in the 10th round of his bout against Charles Conwell, and subsequently underwent brain surgery.
DiBella said in a statement on his website: "Patrick Day passed away today, succumbing to the traumatic brain injury he suffered in his fight this past Saturday, October 12, at the Wintrust Arena in Chicago, IL.
"He was surrounded by his family, close friends and members of his boxing team, including his mentor, friend and trainer Joe Higgins."
Day had previously been knocked down twice in the contest before succumbing again to a left hook midway through the 10th round.
He was treated on the canvas for several minutes before being removed from the ring on a stretcher, and underwent surgery that night.
Earlier, Conwell had written an emotional letter on Instagram praying for Day's recovery and revealing he was considering quitting the sport.
British promoter Eddie Hearn tweeted: "Devastated to hear the news of the passing of Patrick Day. I met him for the first time last Thursday, what a charming young man with a dream and a smile that lit up the room. Our deepest prayers are with his family, his trainer Joe Higgins, Charles Conwell and promoter Lou DiBella."