NASHVILLE, Tenn. >> Marcus Mariota has shown flashes of brilliance during his brief NFL career.

He had a perfect passer rating in his NFL debut and led a 19-point comeback for his first playoff victory.

Now Mariota heads into his fourth season with only his fifth-year option on his contract guaranteed.

It’s time for Mariota to consistently show what he can do, especially after the Titans hired a new coach in January to put the quarterback into an offense that better fits both his arm and legs.

“I don’t focus on trying to prove anything,” Mariota said today. “I’ve just got to go out there and do my job.”

Before the Titans make a long-term commitment with a much larger contract, Mariota starts a window Sunday in the season opener in Miami to show if he really is their franchise quarterback. Even though he has had to learn his third offense in four years, that hurdle may not help get him beyond the $20.9 million he is due in 2019.

Mariota already has won 20 games, most by any quarterback in his first three years with the franchise since George Blanda won 28 in this team’s first three seasons. He also has a chance to become the franchise’s first quarterback to lead the team to the playoffs in back-to-back years since Steve McNair in 2002 and 2003.

But Mariota is coming off a season where he had more interceptions (15) than touchdowns (13) for the first time in his career. He also has yet to play in all 16 games in a regular season.

The Titans hired Mike Vrabel to replace Mike Mularkey in January , and Vrabel hired Matt LaFleur as his offensive coordinator and Pat O’Hara as quarterbacks coach. They worked with Mariota on widening his stance and tweaking his passing mechanics during the offseason to give him more balance when throwing, hoping that leads to improved accuracy.

“He’s done a good job,” O’Hara said. “He’s picked up a lot of good traits, and he feels good about it and he believes in it. We’re ready to go.”

Mariota is ready to go. He missed last year’s trip to Miami, a 16-10 loss, with an injury.

“This is what you work hard for,” Mariota said. “Everything that you’ve done this offseason, you have an opportunity to go out there and kind of show what you’ve done. I’m excited. I’m excited for this team and I look forward to the challenge.”

Dolphins coach Adam Gase has the challenge of preparing for Mariota in a new offense with the Titans tipping nothing in the preseason.

“It is difficult because there are a lot of options that can take place to where it could be just normal drop-back pass., it could be zone read, it could be play-action where if we’re not really doing a good job with our rush lanes and something opens up, he takes off,” Mariota said.

Teammates insist Mariota has nothing to prove to them. This is the quarterback who threw a block for Derrick Henry in their comeback victory in Kansas City, a game where he also scored after catching his own pass.

“I think Marcus is always cool and collected,” three-time Pro Bowl tight end Delanie Walker said. “He’s going to go out there and play his game. Again, we’re paid to make our quarterback look good. He’s going to need our help for that. We just need everybody to make plays, and Marcus will be all right.”

Two-time Pro Bowl left tackle Taylor Lewan said Mariota already has shown plenty.

“I think the confidence as never swayed anywhere other than we have full confidence in Marcus,” Lewan said. “He’s our quarterback. We’re very lucky to have him.”

Vrabel takes a slightly different approach. The coach said every player and coach should be trying to prove his value every day.

“That’s just the approach we have to take,” Vrabel said. “Every day we’re trying to prove our value to the team. If Marcus didn’t come to work tomorrow, everybody would notice. You never want to be a guy that when you didn’t show up for work or you were late, nobody really noticed.”