The NFL player who suffered a cardiac arrest during a game is "beginning to awaken" and has communicated with his medical team.
Doctors said although Damar Hamlin is still on a ventilator and therefore cannot talk yet, the Buffalo Bills player asked doctors in writing which team won the game.
Hamlin, 24, collapsed on the pitch during a game in Cincinnati on Monday after a tackle he made, and required 10 minutes of CPR on the pitch.
In a medical update, Dr Timothy Pritts and Dr William Knight of the University of Cincinnati Medical Center said it appears Hamlin's "neurological condition and function is intact".
Dr Pritts said: "We would like to share that there has been substantial improvement in his condition over the past 24 hours.
"We had significant concern about him after the injury and after the event on the field and he is making substantial progress. As of this morning, he is beginning to awaken and it appears that his neurological conditional and function is intact."
They added that Hamlin woke up on Wednesday night and asked via writing whether the Bills won the game.
Doctors responded to him: "The answer is yes, Demar, you won. You've won the game of life."
One doctor said the fact that his first question was about the outcome of the game showed, "it's not only the that lights are on - he's home."
Hamlin remains in an intensive care unit and has movement in his hands and feet, doctors said.
Bengals' wide receiver Tee Higgins, who collided with Hamlin in the incident, said he is "in a good place right now" after hearing about Hamlin's improvement.
In his first comments since the incident, Higgins said: "It's been hard, just because I had something to do with the play and whatnot.
"But everybody has been making me feel whole again. I talked to his mom and notice everything is OK. He's doing good."
The defensive back collapsed on the field after he was injured when making a tackle during a match against the Cincinnati Bengals.
Hamlin then managed to get to his feet and appeared to adjust his helmet before tumbling backwards and lying motionless.
The Bills said his heart stopped, before his heartbeat was then "restored" on the pitch by medical staff.
His football shirt was cut off, and he was reportedly given oxygen.
The game was suspended, and later postponed, with the Bills' match against the New England Patriots this weekend set to go ahead as planned.