MIAMI -- Miami Dolphins quarterback Tua Tagovailoa has been ruled out for Sunday's wild-card game against the Buffalo Bills, coach Mike McDaniel said Wednesday.

The third-year pro has been in the concussion protocol since Dec. 26 after suffering his second documented concussion of the season the day before in a loss to the Green Bay Packers. McDaniel said that Tagovailoa has not been cleared to resume any sort of football activities and that because of the amount of time he has already missed, McDaniel was able to rule him out.

McDaniel said the Dolphins are preparing for rookie Skylar Thompson to make his third career start Sunday; veteran Teddy Bridgewater is still working his way back from a dislocated pinkie finger on his throwing hand, and his possible availability is unclear.

The team signed nine-year veteran Mike Glennon to its practice squad last week.

There has been no established timeline for Tagovailoa's return over the past two weeks, as McDaniel said medical professionals have advised him it's critical that Tagovailoa focus "solely on the day he's in." The first-year coach declined to speculate on Tagovailoa's playing career, saying he is focused on the quarterback "getting to full health as a human being."

Miami drafted Thompson in the seventh round in 2022 out of Kansas State, and the 25-year-old has made six appearances this season. The Dolphins' Week 18 victory over the New York Jets represented the first time he played an NFL game start to finish, and McDaniel called attention to the difficulty of what has been asked of the rookie.

"I'm not sure if anyone really understands the gravity of what he was able to accomplish," McDaniel said. "He's banking on reps that he's doing individually after practice every single day, some scout-team reps and then everything he did in the preseason. To jump into a fully operating machine and then to do it -- I'm very aware of the score, but we're talking about no turnovers, one sack. ... It was no easy test. Those who are weak would be exposed immediately.

"The way Skylar thinks, he hopes it's the worst game he ever plays."

At Caesars Sportsbook, the point spread on the game moved from Bills -9 to -12.5 immediately after Tagovailoa was ruled out and was continuing to climb Wednesday afternoon. The line, which opened at Buffalo -11 but dipped down to -9 early in the week, was as high as -13 Wednesday afternoon, while the over/under total dropped from 46.5 to 43.5 on the Tagovailoa news.

Pro Bowl left tackle Terron Armstead has missed the team's past two games, and McDaniel said that the veteran is "progressing" but that it's still too early to determine whether he will play this Sunday.

ESPN's David Purdum contributed to this report.