Boxer Patrick Day’s manager says he is in “extremely critical condition” and remains in a coma after being knocked out in the ring over the weekend.

According to Huffington Post, on Sunday, Day was fighting against defending champion Charles Conwell during a USBA super welterweight title bout in Chicago, when he was struck with a right hand that stunned him and then “floored the challenger with a left hook in the 10th round.”

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ESPN reports that the 27-year-old Freeport, N.Y., native was hospitalized with a “traumatic brain injury,” according to DiBella Entertainment, his management team. He is also said to have suffered seizures on the way to the facility and had to undergo emergency surgery.

“Patrick’s condition is extremely grave,” Day’s trainer, Joe Higgins, said Sunday. “He is fighting for his life. That’s all we can really say right now.”

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Day was an alternate on the 2012 Olympic team and has a record of 17-4-1 with six victories coming by knockout. Saturday marked only the second time he has ever lost by knockout.

As his opponent, Conwell expressed concern for Day in an interview right after he was taken out of the ring on a stretcher, and elaborated on his feelings in a heartfelt letter he penned to Day and posted on social media.