American boxer Patrick Day died Wednesday after suffering a serious brain injury during his knockout defeat to Charles Conwell last weekend, promoter Lou DiBella said in a statement.

The 27-year-old super welterweight had undergone emergency surgery after being knocked out by Conwell on Saturday at Chicago's Wintrust Arena. Day, who had been in a coma following surgery at Northwestern Memorial hospital, died surrounded by family and friends. The American fighter had been carried unconscious from the ring on a stretcher on Saturday following his 10th round knockout.