NASHVILLE, Tenn. - The Tennessee Titans have kicked their youth movement into high gear with rookie Zach Mettenberger starting at quarterback against the Houston Texans on Sunday.

Jake Locker has missed three of the past four games with injuries, and coach Ken Whisenhunt said Thursday that the decision to go with Mettenberger was made Tuesday. The coach said this is an opportunity to see what the sixth-round draft pick out of LSU can do with the Titans struggling at 2-5.

"No question he's a talented, young player, and maybe it'll give us a spark," Whisenhunt said. "Offensively, we haven't exactly been lighting it up, so that's part of it in consideration."

Whisenhunt waited to announce the change to make sure Locker — who has been sidelined with an injured thumb — is healthy enough to back up Mettenberger. The coach also was trying to buy a day to slow down the Texans' preparation for the rookie. The shake-up dropped Charlie Whitehurst, who started three of the past four games with the Titans losing two of those, to third on the depth chart.

Mounting losses and injuries seemed to make the change inevitable.

The Titans had stuck with Locker, the eighth pick overall in 2011, since hiring Whisenhunt in January. But Locker has missed 17 of a possible 39 starts and finished only three games this season because of injuries.

Mettenberger will become the fourth rookie quarterback to start in the NFL this season, the third quarterback for Whisenhunt. The Titans already are starting left tackle Taylor Lewan, linebacker Avery Williamson and running back Bishop Sankey with Mettenberger the fourth of six draft picks to start this season.

The quarterback dropped to the sixth round after tearing his left ACL on Nov. 29 playing for LSU but led the NFL this preseason with 659 yards passing. The rookie shaved the beard he started growing during training camp after practice just before talking to reporters.

"By no means am I a Tom Brady or a Peyton Manning," Mettenberger said as he leaned back against his locker. "This is going to be my first game, so really I just got to get the ball out of my hands quick, avoid turnovers and put the ball in the (hands of) guys who can make plays for us. Really that's the biggest thing a young guy's got to do."

Whisenhunt had promised he would be more patient with quarterbacks in his second time around as a head coach. He reached the 2009 Super Bowl in Arizona with Kurt Warner, but the coach cycled through quarterbacks after the veteran left. Whisenhunt started Kevin Kolb, John Skelton, Ryan Lindley and finally Brian Hoyer in his final season in 2012.

Once in Tennessee, he inherited Locker who was coming off a Lisfranc injury to his right foot that cost him the final seven games of the 2013 season. The Titans did not pick up Locker's option for 2015 in May, even as they stood behind him as their starter.

But Locker hurt his right wrist in a loss at Cincinnati on Sept. 21. He missed a loss at Indianapolis and then started Oct. 5 against Cleveland where he threw for a touchdown and ran for another TD before hurting his right thumb on a helmet.

"I understood after last year I didn't know kind of how it would go and coming into this year they gave me an opportunity," Locker said. "I haven't been in. I haven't played. That's been kind of one of those things that I've dealt with throughout my career, and I imagine it has something to do with that."

Fans have been clamouring to see Mettenberger with the Titans losing five of their last six. This franchise also needs to give people a reason to use their tickets and come to the stadium where they have won only two of their last nine home games.

Mettenberger fits the profile of the quarterback Whisenhunt has had the most success with: Pittsburgh's Ben Roethlisberger. Mettenberger is 6-foot-5 and 224 pounds who can stand in the pocket, and he has a strong arm throwing for 3,082 yards last season at LSU. With Locker's injured thumb, Mettenberger also had taken some practice work with the starters over the past two weeks.

He will be the first rookie this franchise has started since 2010. Rusty Smith started at Houston after Vince Young was placed on injured reserve and veteran Kerry Collins was hurt. Smith and the Titans lost 20-0.

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Follow Teresa M. Walker at www.twitter.com/teresamwalker