NASHVILLE, Tenn. >> The Jacksonville Jaguars already have fallen quickly, from being a win away from their first Super Bowl berth in January to last in the AFC South in December.

The Tennessee Titans desperately want to avoid joining them as a one-and-done playoff team, especially after sweeping the Jaguars last season.

“That’s something we can’t allow to happen,” Titans defensive lineman Jurrell Casey said. “We want to keep them where they’re at — at the end of the division and leave them there. We got to make sure we take care of our part. At the end of the day, we can’t worry about them. We have to worry about ourselves because we ain’t played so hot this year ourselves.”

That’s very true. The Titans (6-6) had to rally from 16 points down to beat the Jets 26-22 to snap a two-game skid. Tennessee likely needs to win out and get some help with four teams between the Titans and the second AFC wild-card berth they earned last season.

The Jaguars (4-8) may not be mathematically finished just yet after snapping a seven-game skid with a 6-0 shutout of Andrew Luck and the Colts last weekend. Cody Kessler now has a start under his belt, and running back Leonard Fournette will be back from suspension, too. But the Jaguars have lost three straight and five of the last six to Tennessee.

“Three straight times?” Jaguars linebacker Telvin Smith said. “Dang. We’re going to go out and make sure we get the win. That’s all we’ve got to focus on.”

Some things to know about the Jaguars and Titans:

FOURNETTE RETURNS

Yes, Fournette is back after a one-game suspension without pay, which cost the second-year pro nearly $100,000. Getting that extra time off could pay dividends considering most everyone else on the field played four days earlier. The Titans also have allowed 281 and 156 yards rushing over the past two games.

“Fournette should be very fresh and have a little pep in his step, and hopefully he can give us a spark that we need,” Jaguars defensive tackle Calais Campbell said.

CONTAINING MARIOTA

Titans quarterback Marcus Mariota has burned the Jaguars with his feet, including an 87-yard touchdown run in 2015. Mariota has a combined 135 yards rushing in Tennessee’s three-game winning streak in the series, including 51 in Week 3’s 9-6 victory. Mariota also led the Titans with 43 yards rushing last week against the Jets and threw for 282 yards.

“Super challenging,” Jaguars cornerback Jalen Ramsey said. “You just have to cover for even longer. It’s kind of like a scramble drill. It will turn into backyard football with made-up routes to try to get open and help their quarterback out, so it makes it tough on us.”

DEFENSIVE SHOWDOWN

These are two of the NFL’s best defenses, with the Jaguars having just posted the league’s fourth shutout this season. The Jaguars rank third in both fewest overall yards allowed and passing yards. The Jaguars also are the NFL’s fifth-best scoring defense, just a spot ahead of the Titans, who have allowed only 26 touchdowns. That’s tied for third fewest in the NFL.

The Titans lead the NFL in red zone defense; they hold opponents to TDs on just 44.1 percent of trips inside the Tennessee 20.

HARRISON SHINES

Jaguars rookie Ronnie Harrison was one of several defensive bright spots last week. The safety had three tackles, including a sack on a fourth-down play, in his first career start. Harrison will remain in the starting lineup against the Titans.

“His game, his awareness, he never let the moment get too big for him,” fellow safety Tashaun Gipson said. “He stepped in and seized the moment. Obviously, he had a big, huge play for us at the end. You can’t script a better first start for a guy like that.”

HOME COOKING

The Titans have won 14 of their last 17 at home, and they’re hoping to lean on that edge with three more home games down the stretch. Linebacker Brian Orakpo made a plea to fans to turn out and be loud from the start.

“We need that help,” Orakpo said. “We need that energy, we feed off our crowd. I know it’s been times where we don’t give them nothing to cheer about. But if they come ready, they come loud, they come just prepared like we’re going to be prepared, it’s going to be a long day and a hard day for the Jags and give us that true real home-field advantage.”