San Francisco 49ers defensive coordinator Robert Saleh met with reporters on Thursday and discussed Sunday's matchup against the Tennessee Titans. The defense will be tasked with stopping a dangerous running game that includes Titans running backs Derrick Henry and Latavius Murray -- not to mention quarterback Marcus Mariota.

Tennessee is averaging 117.7 rushing yards per game, which ranks 10th in the NFL. They are ranked seventh in the league in yards per carry (4.4) and only one team, the New Orleans Saints, have more rushing touchdowns (NO - 19, TEN - 17).

"They have a large, probably the biggest run-game playbook I've ever seen on tape," Saleh said. "They come at you many different ways. This is going to be a great game with regards to locking in on your keys and trusting your fundamentals, being great with your eyes and understanding your responsibility. You've got to be very sound fundamentally and structured on defense to ensure your gap integrity is in good shape."

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Mariota has completed 62.2 percent of his passes for 2,582 yards, 10 touchdowns, and 14 interceptions this season. This season is the first in Mariota's three-year career where he has thrown more interceptions than touchdowns. Eight of this season's interceptions have come over the past four weeks.

"A lot of times there's tipped balls from Mariota," Saleh said. "He's been unlucky. I'm not in their meetings to know whether or not a receiver busted a route or not. Having gone against Mariota in the past at Jacksonville, he is a very talented quarterback and I know we as a defense are going to have our hands full and we're excited for the challenge."

What is it that makes the Titans' run-game playbook so difficult to defend?

"They shift you. They motion you," Saleh said. "They do everything they can to get you out of your gap and get you confused on what your responsibility is. For us, repping all that stuff and being sound is going to be the challenge."

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Another big part of the Titans offense is former 49ers tight end Delanie Walker. Of course, his seven seasons in San Francisco were long before Saleh's time – or any of the members of this coaching staff's. Saleh discussed what makes Walker so dangerous.

"Delanie is a weapon," Saleh said. "They use him a lot in different ways. But, he's definitely a focal point of their offense and a guy that we have to deal with, as well as the other guys with DeMarco Murray and Henry and all that. Again, it's a challenge for us. I feel like our guys are ready."

The 49ers and Titans kick off on Sunday at 1:25 p.m. PT at Levi's Stadium.