CHICAGO (AP) — Boxer Patrick Day died Wednesday, four days after sustaining head injuries in a fight with Charles Conwell.

Promoter Lou DiBella said Day died at Northwestern Memorial Hospital. He was 27.

“He was surrounded by his family, close friends and members of his boxing team, including his mentor, friend and trainer Joe Higgins,” DiBella said in a statement on his website. “He was a son, brother, and good friend to many. Pat’s kindness, positivity and generosity of spirit made a lasting impression with everyone he met.”

Day had brain surgery after being knocked out in the 10th round Saturday night at Wintrust Arena. Knocked down twice earlier in the bout, the junior middleweight was taken from the ring on a stretcher.

Two days after the fight, Conwell posted a heartfelt message to Day on social media.