Damar Hamlin showed "remarkable improvement" over the past 24 hours but remains critically ill, the Buffalo Bills said on Friday (NZ time), after the safety suffered cardiac arrest on the field during an NFL game in Cincinnati on Tuesday.
"Per the physicians caring for Damar Hamlin at the University of Cincinnati Medical Center, Damar has shown remarkable improvement over the past 24 hours," the Bills said.
"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," the team said.
During the first quarter of the Bills' penultimate regular season game against the Bengals, Hamlin got to his feet after making a tackle and then collapsed.
After having his heartbeat restored on the field, Hamlin was transported to the University of Cincinnati Medical Center where he has remained in intensive care.
The game, which Cincinnati led 7-3, was later postponed.
The positive update will be welcome news for the Bills, as they prepare for their final regular season contest on Sunday, and for sports fans across the United States and around the world who have rallied behind the 24-year-old safety.
Fans, athletes, celebrities and politicians, including U.S. President Joe Biden, have all offered Hamlin their prayers and support.
Famed Niagara Falls - both the American Falls and Canadian Horseshoe Falls - were illuminated in Bills blue on Tuesday as a show of support for Hamlin, the Bills and nearby city of Buffalo.
The NFL has not yet made a decision on whether to replay the Bills and Bengals game.
The postponed game, if played, would have playoff implications for both the Bills and Bengals, who are battling with the Kansas City Chiefs for the top seed in the American Football Conference, which comes with a first-round playoff bye.
The Bills are scheduled to host the New England Patriots on Monday.