Hamlin collapsed on the field during a Monday night game in Cincinnati and had to have his heartbeat restored but began to wake up two days later and has had his breathing tube removed.

The 24-year-old Hamlin also surprised his team mates on Friday when he appeared on a video call during which he said "love you, boys," flexed his biceps and flashed a heart symbol with his hands.

"Damar Hamlin's inspiring progress over the past few days has lifted the spirits of the entire NFL and football fans across the country," Goodell wrote in the open letter that was posted on the league's website.

"While his recovery is just beginning, we thank the NFL medical personnel and the medical staffs from both teams whose emergency action quite likely saved his life.

"We are also grateful to the professionals at the University of Cincinnati Medical Center who tended to Damar and continue to oversee his care."

Goodell also said players and coaches from all 32 NFL teams will wear "Love for Damar 3" T-shirts during pregame warmups in a show of support for Hamlin this weekend as the league's regular season comes to a close.

Buffalo could still secure the top seed in the American Football Conference and coveted first-round bye if the Kansas City Chiefs lose to the Las Vegas Raiders later on Saturday and the Bills beat the New England Patriots on Sunday.

"I'm deeply hopeful that with his continued progress, there is a good chance Damar himself will be watching his teammates," wrote Goodell. "We are grateful for and humbled by all who played a role as he continues on his road to recovery."