NASHVILLE, Tenn. (AP)The Tennessee Titans appear set to find out just how much rookie quarterback Malik Willis has grown since his previous NFL start.

With veteran Ryan Tannehill one of 17 Titans on their lengthy injury report, they also may wind up learning if the rookie can help extend their streak as AFC South champs.

Tannehill, who needed a walking boot after first spraining his right ankle Oct. 23, proved his toughness by taping up that same ankle yet again after being carted to the locker room last week and returning to finish the game. He said after the loss to the Chargers the pain he felt was at the ”top reading on the pain scale.”

The veteran missed both a second straight practice Wednesday and his regular session with reporters.

The Titans (7-7) signed Joshua Dobbs off the Detroit practice squad Wednesday, giving them a fourth quarterback with Kevin Hogan on the practice squad. Coach Mike Vrabel said Dobbs gives the Titans a chance to strengthen and add depth to the quarterback position.

”Obviously, with what Ryan in his situation, we’ll still monitor that and try to make sure that he’s doing everything he can to try to get to the game,” Vrabel said. ”And if not, that we have guys in here that can they’ll be able to help us and develop in our system.”

The Titans’ lead atop the division they’ve won the past two seasons has dwindled to one with a four-game skid. They host the Houston Texans (1-12-1) on Saturday – the same team Willis made his first NFL start against Oct. 30 in a 17-10 win against Houston.

That day, the third-round draft pick out of Liberty threw only one pass in the second half. Derrick Henry, the two-time NFL rushing champ, led the way, running for 219 yards and two touchdowns on 32 carries. The Titans finished with 314 yards rushing – the second-best total in franchise history.

Willis also started a 20-17 overtime loss to the Chiefs in prime time in Kansas City. He came off the bench last week and was 3 of 4 for 20 yards while running once for 8 yards while Tannehill got his ankle taped up. If he gets to start against a team he’s already faced, Willis said it would be a ”really cool opportunity.”

”I mean, yeah, my first start was against them, but not too much though matters,” Willis said. ”It’s a little bit in the past. It’s about going out there and preparing for them this week. They’ve been playing hard games against these last few teams they’ve been playing and you just got to respect them.”

Offensive coordinator Todd Downing said Willis, the 86th pick overall in April, has been growing weekly in his confidence and command of the huddle. Willis has been running the scout team all season as Tannehill’s backup, and Downing said he’s very pleased with the progress Willis has made.

The Titans likely will need Willis’ mobility Saturday as they try to stay ahead of Jacksonville (6-8). Houston is last in the NFL defending the run, and Willis ran for 2,131 yards and 29 touchdowns combined between stints at Auburn and Liberty.

Willis says going against a Titans’ defense has helped him grow. He also says they can’t expect the Texans to defend them the same way as the previous game.

Houston coach Lovie Smith warns his Texans ”can’t chase too many ghosts” even as they know the skillsets of both Willis and Dobbs.

”Their offense goes through their tailback no matter who the quarterback will be,” Smith said.

NOTES: The Titans placed second-year offensive lineman Dillon Radunz (knee) on injured reserve before practice, putting that list at 17. All five starting offensive linemen are on the injury report with LT Dennis Daley added Wednesday as limited by an abdominal injury. RG Nate Davis (ankle) and C Ben Jones (concussion) did not practice. LG Aaron Brewer (rib) and RT Nicholas Petit-Frere (ankle) both were limited. … WR Treylon Burks (concussion protocol) practiced fully for a second straight day. DL Denico Autry, who has missed four games, practiced fully.

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