Jaguars defensive end Andre Branch will miss "significant time" early in the season after spraining a knee ligament.

Coach Gus Bradley made the announcement Saturday, one day after Branch was injured during a preseason game against Detroit. Branch sprained the medial collateral ligament in his left knee early in the game, when teammate Aaron Colvin landed on him.

"He could miss significant time," said Bradley, who didn't have a timeframe for Branch's return. "I think we'll find out more. I know he's got to go through the diagnostic process. Until they get all that information, I'm just going off the same thing as you: significant time."

It's the latest setback for Jacksonville's defensive line, which already is without rookie defensive end Dante Fowler Jr. and defensive tackle Sen'Derrick Marks.

Fowler, the third overall pick in the draft, is out for the season after tearing a knee ligament in May. Marks has been sidelined since injuring his knee in last year's season finale. It seems unlikely Marks will ready for the Sept. 13 opener against Carolina.

"I think there are barriers that we have to overcome to get him to that point," Bradley said. "But in his mind he's going to be ready. And in our doctors' and trainers' mind, he's got a shot, and that's just what we're going off of. Is it a challenge, an uphill battle? Yes it is."

Branch, meanwhile, was considered the starter at Jacksonville's "Leo" position, a key spot in Bradley's defensive scheme.

Although Branch totaled just 75 tackles and 10 sacks in his first three seasons, the former second-round pick from Clemson had shown signs of progress in training camp and the preseason.

"That's a tough one on us," Bradley said. "The timeframe we're looking at, I'm not sure. I know he's not going to be ready for the first game. Guys will step up. But it's probably tough when lose a guy like that. He was playing well in training camp. ... It's always tough. But we said that you can never have enough rushers, and some guys will have to step up."

Veteran Chris Clemons, third-year pro Ryan Davis and 2014 fifth-round pick Chris Smith are options to replace Branch.

Bradley made it clear he would prefer to keep Clemons and Davis as mostly third-down pass-rushers. He added that Smith could be a better option on first and second downs.

The Jaguars also could look elsewhere for help, maybe sign a veteran free agent or someone released in upcoming roster cuts.

"We did talk about personnel, but we didn't get into those discussions," Bradley said. "We just talked about possibilities and all the options that could play out in front of us. We didn't get to going outside."