Tagovailoa previously missed weeks five and six after suffering another concussion, in an incident that gripped the National Football League (NFL), prompting outrage from fans as the league and its players union moved to adopt enhanced concussion protocols.

McDaniel told reporters that he and his staff grew concerned about Tagovailoa after reviewing film from the Dolphins 26-20 loss to the Green Bay Packers on Christmas Day and questioned the former first-round pick on Monday before having him meet with a doctor.

"This is just a day at a time process - his health is the first, foremost and only priority," said McDaniel.

"There was some things that caused us to really prod and as a result we felt like he needed to see medical professionals."

McDaniel, who took the reins this year in Miami, said there was no timeline for Tagovailoa's return and told reporters that watching him struggle was "terrible."

"In moments like this you lean on medical professionals and I stopped even thinking about anything but each day," he said.

Sunday's game on the road in New England is critical for the Dolphins' playoff hopes, as their record stands at 8-7. They last reached the postseason in 2016.