Suffering with back and ankle problems, Tagovailoa has only been able to play a limited part in preparation this week.
Dolphins coach Mike McDaniel asserted on Monday it was the 24-year-old Tagovailoa's injured back that caused him to stumble to the ground in Sunday's 21-19 win over the Buffalo Bills, amid fears of a concussion.
Tagovailoa took a hard hit in that game, as Bills linebacker Matt Milano pushed him to the ground. Tagovailoa's helmet slammed into the turf, but he rose to his feet quickly. However, he then shook his head, appeared woozy and lost balance as he stumbled back to the ground.
The 24-year-old quarterback went to the locker room to be assessed by the team's medical staff, with the Dolphins announcing a head injury.
He returned for the start of the third quarter – a move that prompted the NFL and National Football League Players Association to conduct a joint review of how the decision was made to allow Tagovailoa to return.
McDaniel maintained, however, that proper protocols were followed and Tagovailoa was cleared by the team and the independent neurologist.
Tagovailoa said after the game that it felt like he hyper-extended his back earlier in the contest, which was why his back locked up on him after the hit from Milano, causing the stumble.
The Dolphins have Teddy Bridgewater on standby to start on Thursday.
McDaniel was hoping to make a decision on Wednesday about his starting quarterback, but said it might have to come down to an early call on Thursday instead, stressing he would back 29-year-old Bridgewater to come good if called upon.
"We have a bunch of faith in him. So we're walking through in general, anyway," McDaniel said on Tuesday. "So Teddy has to take reps each and every play in terms of calling the play and visualising everything as it stands.
"We'll probably just take it as long as we have to before we can be convicted. But at some point there has to be [a decision] – it won't be five minutes before kick-off, I know that. Probably some time on Wednesday, but if we have to, we'll move it to Thursday morning."