Dolphins' Tagovailoa clears concussion protocol. But the Dolphins are losing a top defender

Dolphins quarterback Tua Tagovailoa passed the concussion protocol on Thursday and will start Sunday against visiting Arizona (1 p.m., Fox).

And he will have his two best targets at his disposal. Coach Mike McDaniel said he is “very optimistic” that Tyreek Hill (foot) and Jaylen Waddle (quadriceps) will play Sunday after being able to practice on a limited basis this week. (Hill was later listed as questionable.)

But the Dolphins suffered a major injury setback this week: Defensive player Zach Sieler was stabbed in the eye during practice on Thursday and is out for Sunday's game. According to NFL Network, Sieler suffered a fractured eye socket.

McDaniel said he doesn't know when Sieler will be able to play again, calling it “week to week.” McDaniel said it was the first time in his coaching career that he had experienced such an injury.

Da'Shawn Hand will likely play alongside Calais Campbell more often in Sieler's absence. Benito Jones and Brandon Pili are the other defensive lineman on the 53-man roster.

The Dolphins likely need to add one of two defensive tackles to the practice squad: newcomer Matt Dickerson (who played in 36 career games last season, including 12 for Kansas City) or Neil Farrell, a 2022 Raiders fourth-round pick from LSU. Farrell, who is 6-4 and 325 pounds, has 13 tackles in 12 NFL games for the Raiders and Chiefs.

Long-snapper Matt Overton is expected to be the Dolphins' second promotion on Sunday, as Blake Ferguson misses at least four games for personal reasons.

Meanwhile, Tagovailoa will play Sunday against Buffalo for the first time since his fourth documented concussion and possibly his fifth on Sept. 12.

He followed the NFL's strict five-step Return to Participation protocol. After Thursday's practice, Tagovailoa was examined by an independent neurological consultant and cleared to play Sunday.

While he went through the protocol, Tagovailoa was mentored by several leading medical experts across the country.

His decision to return to the game after receiving medical clearance was made with his doctors and family.

“Zero [doctors] “I recommended that he not play football,” McDaniel said. “It boosted his confidence.”

The Dolphins must clear a spot on the 53-man roster for Tagovailoa by Saturday at 4 p.m.

Skylar Thompson is on track to be Tagovailoa's replacement on Sunday, although McDaniel said he wants to watch Friday's practice before selecting a No. 2 quarterback. Thompson, returning from a chest and rib injury, said he is now pain-free and is preparing to be the backup QB on Sunday.

McDaniel addressed other issues:

▪ Outside linebacker Emmanuel Ogbah (biceps) and safety Jevon Holland (hand) are expected to play Sunday after missing last game, McDaniel said.

▪ Cornerback squad Kohou (neck) is out Sunday and cornerback Storm Duck (ankle) likely won't play, McDaniel said. Jalen Ramsey could play more in that slot to replace Kohou; Holland is another option.

In fact, McDaniel talked about the possibility of “Jalen playing nickel or Jevon Holland or players at other positions to unbalance the offense and utilize your really good players and put them in positions to succeed.”

Cam Smith and Siran Neal are also available as backup cornerbacks behind Ramsey and Kendall Fuller.

▪ Guard Liam Eichenberg, who dealt with two shoulder injuries this week, will play Sunday, McDaniel said.