Tagovailoa was placed in concussion protocol a day after the Dolphins' 26-20 loss to the Packers. Dolphins head coach Mike McDaniel later said doctors found that Tagovailoa, who finished the game, had suffered a concussion.

McDaniel previously told reporters that backup Teddy Bridgewater was in line to start on Sunday against the New England Patriots.

"The review established that symptoms of a concussion were neither exhibited nor reported until the following day at which time the team medical personnel appropriately evaluated and placed Mr Tagovailoa in the concussion protocol," the NFL and National Football League Players Association (NFLPA) said in a joint statement.

Tagovailoa suffered another concussion earlier this season, missing weeks five and six, in an incident that gripped the league prompted the NFL and NFLPA to adopt enhanced concussion protocols.

The protocol, which is reviewed annually, is initiated when "a player receives an impact to the head and exhibits or reports signs or symptoms suggestive of a concussion," the statement added.

There is no set timeline for a player's return to participation from concussion. Players in protocol are limited from team activities and not eligible to play until cleared by medical professionals.

The NFL reported 187 concussions during the 2021 pre-season and regular season, down from the 281 reported during the same time frame in 2017.