DAVIE, Fla. -- Miami Dolphins rookie quarterback Tua Tagovailoa was downgraded from questionable to doubtful for Sunday's game vs. the New York Jets due to a left thumb injury that he suffered during practice this week.

Veteran Ryan Fitzpatrick is expected to start for Tagovailoa.

The Dolphins elevated rookie practice squad quarterback Reid Sinnett to the active roster for the first time this season, another sign that Tagovailoa is expected to be inactive Sunday. Sinnett would serve as Fitzpatrick's backup in his first NFL game.

Tagovailoa jammed the thumb on his left throwing hand on a teammate's helmet during Wednesday's practice, which limited him throughout the week, although he was seen throwing and practicing every day.

Dolphins Brian Flores initially said Thursday morning he wasn't "too worried" about Tagovailoa's thumb but Friday he noted he would have to watch his effectiveness in practice film before deciding if he could play Sunday.

Clearly, Flores didn't like what he saw, and the Dolphins are leaning toward giving Tagovailoa time to rest the thumb.

Fitzpatrick started the first six Dolphins games this season, putting together a 3-3 record and generally performing well before Flores surprisingly elevated Tagovailoa to be the starter beginning in Week 8 vs. the Los Angeles Rams. Tagovailoa has gone 3-1 as a starter since taking over, but he was benched in the fourth quarter of Sunday's 20-13 loss to the Denver Broncos due to performance.

The expectation was that Tagovailoa would return to the starting lineup for a chance to rebound this Sunday, but the thumb injury spoiled that opportunity. Now Fitzpatrick, who just turned 38 this week, will try to get the 6-4 Dolphins an important win against the 0-10 Jets as they try to remain in thick of the AFC playoff picture.

Since Tagovailoa is a left-handed passer, any injury to his left thumb makes it difficult to consistently throw the ball accurately. Flores also mentioned earlier this week that every player responds differently to injuries.

"I can't say specifically for Tua or any player on exactly what they can play through or not play though," Flores said. "I know he's a tough kid. He wants to play, and we'll see how this goes."

For Tagovailoa, his chance to rebound from a poor showing will have to wait. Attention turns toward how long it takes for Tagovailoa to rehab his thumb and return to play. It's worth noting the Dolphins brought in quarterback Jake Rudock, who spent parts of 2019 and 2020 on the team's practice squad, for a visit Friday.

In the meantime, it's FitzMagic time.