Day was taken to a hospital after getting viciously knocked out in the 10th round by Conwell in Chicago on Saturday night.
According to ESPN, Day was in a coma after an emergency operation on his brain, although it is not known if it was medically induced.
Day was fighting at super welterweight on the undercard of Oleksandr Usyk’s heavyweight debut win over Chazz Witherspoon by TKO.
Conwell landed a right hand early in the 10th. That caused Day to stumble and seconds later Conwell landed a left hook that knocked Day to the canvas.
Day, from Freeport, New York, was instantly knocked out and it wasn’t clear if he regained consciousness.
He was treated by a doctor in the ring and then was rushed off on a stretcher by paramedics and transported to the hospital. Day was knocked down twice earlier in the fight.
Later, DAZN reported Day never regained consciousness and began having seizures when he entered the ambulance and he was using a breathing tube at the hospital.
‘I had a chance to speak to the doctor, he told us Patrick never woke up on his way to the ambulance,’ DAZN’s Claudia Trejos said.
‘He started seizing on his way to the ambulance, and he has been taken to hospital.
‘Our thoughts and prayers are with Patrick Day and his family.’