The San Francisco 49ers and Jacksonville Jaguars, two NFL teams that face each other on Sunday, have opposite records. The 49ers go into the matchup with four wins and 10 losses while the Jaguars have 10 wins and four losses. One thing both teams have in common is that each is coming off of a three-game winning streak.

The 49ers are riding the success of quarterback Jimmy Garroppolo, who has not yet lost a game as a starter in five games over the past two seasons. The Jaguars are thriving off of a tough defense which ranks first in the NFL in points allowed and against the pass. Jacksonville also has the league's top-ranked rushing attack, which is led by rookie running back Leonard Fournette.

49ers head coach Kyle Shanahan addressed the media on Wednesday and provided a preview of his team's next opponent. He was asked to identify players who make Jacksonville's defense so dangerous?

"All of them," Shanahan answered. "A combination of all of them. They had some low records for a while, and they've done well with their draft picks across the D-Line to their linebackers who are probably as fast as anyone in the league. Their D-Line, they've got Pro Bowlers across it and Pro Bowlers as backups too. They have one of the top corners in free agency last year. They have one of the top corners in the draft two years ago, and they have two good safeties."

Shanahan sees Sunday's game against Jacksonville as a good challenge for his improving 49ers. The Jaguars are a playoff team and are currently the third seed in the AFC. Shanahan looks forward to going against such a challenge.

"I look forward to it a lot, for our whole team," Shanahan said. "I do believe that they have as much qualities as anyone that it takes to win a Super Bowl; a top defense, a very good running game, a good offense, good special teams. When you see a team like that on tape that you believe has that ability, it's a good thing. It's a good challenge for your team to go against them and see where you're at."

One standout has been cornerback Jalen Ramsey, who was the Jaguars' fifth-overall draft pick in 2016. Shanahan explained how Jacksonville uses the young and physical corner.

"They'll be in different spots," Shanahan said. "They're not always in the same spots. Besides that, it's very similar to the coverages we play. They play a lot of three-deep, where they're responsible for the go-route and to stay on top of everything. He's a very physical corner and big corner. He likes to jam. He can get after you that way, and he's a very good tackler. He competes, has very good ball skills. You can see why he was a top pick and why he's had the success he's had so far. He's a guy with his mentality and his skill set, he's only going to get better each year."

Another star of the Jacksonville defense has been former Arizona Cardinals defensive end Calais Campbell, who signed a four-year contract with the Jaguars in March and has 14.5 sacks this season. Shanahan was asked how Campbell's role has changed since his time in Arizona.

"Just playing on the outside more," Shanahan said. "I know he goes on the inside more in nickel and moves around. Just playing him over at Arizona, he was always an inside player. Now to have him over the tight end a lot wasn't totally what I was expecting, and then you turn on the tape, and you see why. He's been a very good player there, and they can move him around and put him wherever they need be in nickel."

Cornerback A.J. Bouye is also a new face on the Jacksonville defense. He joined the Jaguars on a five-year deal in March and lines up opposite Ramsey. Both Bouye and Ramsey were named as 2018 Pro Bowl starters for the AFC. Shanahan shared that Bouye was one of the numerous players the 49ers researched leading up to free agency.

"Yeah, we looked into him," Shanahan said. "We looked into everybody who was a free agent. I definitely know how good he was from last year, just studying him. He's a very athletic guy, very clean feet. He's hard to beat. He stays on top very well and does not give up many big plays."

While Jacksonville possesses the NFL's top-ranked pass defense, it also owns the league's 19th-ranked run defense. Shanahan was asked about the difference between the two areas.

"It's tough to say exactly why," Shanahan said. "They're talented all over. No one's getting many big plays on them in the pass game. I think it's tough to run the ball all the way down the field, but when you can't get a big play in the pass game, I think people are more trying to do that. They've been so good on third down and stuff, that being bad in the run game, not being bad, but not being as good as in the pass game, it really hasn't hurt hem that much because they get off the field on third down or they get a turnover.

"Giving up some yards-per-carry is something defenses never want to do, but if you keep them out of the end zone, then it doesn't matter that much. And the way you do that is you're good on third down, and you create turnovers."