Damar Hamlin "won the game of life" when he survived an on-field cardiac arrest in the Buffalo Bills' game against the Cincinnati Bengals, according to a doctor treating the safety.
Dr Timothy Pritts said Hamlin still needed assistance with his breathing, and the 24-year-old remains in intensive care at the University of Cincinnati Medical Center.
However, he can communicate by writing and Pritts expanded on what the Bills meant when they described Hamlin as "neurologically intact".
"His first note was, 'Did we win?'," Pritts said.
"It's not only that the lights are on. We know that he's home. All the cylinders are firing right in his brain."
Hamlin collapsed after a collision with wide receiver Tee Higgins and had to be resuscitated on the field, before the game was abandoned.
He received "textbook" medical attention at the stadium, Pritts' colleague Dr William A. Knight said.
Pritts explained: "He's made substantial progress. It appears his neurological condition and function is intact. We are very proud to report that, very happy for him and his family and the Buffalo Bills organisation."
Hamlin is receiving extensive medical attention, but Pritts said: "This marks a really good turning point in his ongoing care."
Pritts added: "To paraphrase one of our partners, when he asked, 'Did we win?', the answer is, 'Yes, Damar, you won. You won the game of life.' That's probably the most important thing out of this.
"We really need to keep him at the centre of everything else that's going on. We really want to ensure a good outcome for him."
The hope is that Hamlin is able to get back to the state of health in which he began Monday's game, but there will be no discussions about returning to football for the immediate future.
Knight said: "It's entirely too early to have that conversation. Our focus is on getting him better, getting him extubated and on the road to recovery."
Pritts said Hamlin had been able to "follow commands", as it was confirmed the NFL safety could move his hands and feet.
Although Hamlin has a breathing tube and cannot speak, the positivity from his doctors pointed towards a positive outcome, although it was said he has "many steps" still ahead of him.
Earlier on Thursday, the Bills said in a statement: "Per the physicians caring for Damar Hamlin at the University of Cincinnati Medical Center, Damar has shown remarkable improvement over the past 24 hours.
"While still critically ill, he has demonstrated that he appears to be neurologically intact. His lungs continue to heal and he is making steady progress.
"We are grateful for the love and support we have received."