JACKSONVILLE, Fla. -- Joe Flacco found out in Week 3. So did Ben Roethlisberger two weeks later. This is a much different Jacksonville Jaguars defense than they're used to seeing.

The unit they had little trouble with throughout their careers has become a monster in 2017. The realization left them battered and bruised, both mentally and physically.

The Jaguars' next target is Philip Rivers. The Los Angeles Chargers quarterback has owned the franchise in his career, putting up gaudy numbers and winning games relatively easily. Rivers has won six games in a row against the Jaguars and has put up more than 30 points in five of those six games.

"You're talking about a player that has probably played as well against our team as any player that has ever played," Jaguars coach Doug Marrone said.

Yeah, but he's never faced a Jaguars defense like this before.

Jacksonville leads the NFL in scoring defense (14.6 points per game), pass defense (156.4 yards per game), yards per play (4.6), and sacks (35). The Jaguars have forced 16 turnovers, including 10 interceptions, and have allowed just 10 points over the past 10 quarters.

According to the NFL's Media Research Group, cornerbacks Jalen Ramsey and A.J. Bouye and safety Tashaun Gipson rank in the top six in passer rating allowed in coverage (minimum 20 attempts). Spiking a ball on every play equals a 39.6 passer rating, but Gipson (30.3) and Ramsey (38.2) are below that and Bouye (40.4) is just barely above.

That's nothing like the units that Rivers decimated since he entered the league in 2004. He has completed 71.2 percent of his passes for 2,119 yards and 19 touchdowns with just four interceptions in seven games against the Jaguars. That's an average of 302.7 yards and 2.7 touchdowns per game.

"This is certainly the best group of guys they've had together," Rivers said during his weekly news conference. "They're playing really well, they're playing with a lot of confidence, and they're playing fast. Definitely this seems to be the best Jacksonville defense we've played, but it's been trending in that direction the last few years."

Rivers' first game against the Jaguars was his worst: 55 percent completions, 309 yards, one TD, two interceptions in a 24-17 loss in 2007. He's completed more than 70 percent of his passes in five of the six meetings since and hasn’t thrown an interception since the 2010 game between the teams.

"Why will it be different [this Sunday]?" linebacker Telvin Smith asked. "Because we said it will and we're preparing for it to be different. I think we came into this season again with a lot of expectations and pushing each other and [what] you're seeing is us living up to those [expectations] and continue to push each other in going in the direction we said we would go."

Smith is backed up by what the Jaguars did to Flacco and Roethlisberger this season.

In Flacco's first five meetings with the Jaguars he went 3-2 and completed 68.8 percent of his passes for 1,185 yards and five touchdowns with five interceptions. He was sacked eight times and posted an 85.1 quarterback rating.

The Jaguars routed Baltimore 44-7 at Wembley Stadium in London in Week 3 and Flacco completed just 8-of-18 passes with no touchdowns and two interceptions and was sacked twice before being benched for Ryan Mallett. Flacco posted a quarterback rating of 12.0, which was the lowest passer rating by a quarterback with at least 15 attempts in Jaguars history.

"[The Jaguars] have a good defense," Flacco said after the game. "I've been saying that all week. They play fast, they play hard. They are strong, they're physical. They create issues for a lot of teams. We weren't able to get going early. I thought we could probably take some shots outside, but just weren't able to get it done."

In Roethlisberger's first six games against the Jaguars, he threw for 1,286 yards and 10 touchdowns with three interceptions and a 93.8 passer rating. Yet in a 29-7 victory in Week 5 at Heinz Field the Jaguars intercepted Roethlisberger five times, sacked him twice, and though he completed 60 percent of his passes for 312 yards, Roethlisberger posted a 37.8 quarterback rating.

It was such a thorough beating that it prompted Roethlisberger to speculate, "Maybe I don’t have it anymore."

Will the Jaguars make Rivers wonder the same thing? Can they finally get some payback for the way Rivers has devastated their defense in his career?

"In order to get payback you still have to be worried about what happened," Smith said. "We're not worried about things that happened last year, two years ago.

"... I’m ready to lock in. I'm ready to lock in and go out and just do what we do. As long as we go out and do what we do, continue to prepare the way we prepare, again we're going to be the best team on the field."