JACKSONVILLE, Fla. -- The Jacksonville Jaguars are going to play the rest of the season with several backups on defense, and things could get worse.
The Jaguars placed cornerback Derek Cox on injured reserve Friday with a knee injury, the third defensive starter lost in the last two weeks.
Linebacker Clint Session was placed on injured reserve Tuesday following a second concussion this season. The team also lost cornerback Rashean Mathis to a season-ending knee injury nearly two weeks ago.
Making matters worse, defensive linemen Terrance Knighton and Matt Roth have been ruled out for Sunday's game against Houston. Aaron Kampman also is questionable because of a hamstring injury. Knighton said Friday he is waiting to hear from doctors whether he will play again this season.
"With some of the guys that we're going to play, we'll find out how well we've done in developing some of these guys, how much attention they've been paying," coach Jack Del Rio said. "It is a healthy process to have, where guys understand that they can get that opportunity with hard work and commitment to the team. You hate to have this many guys (injured), but that is the way we approach it as coaches."
Backup cornerbacks Will Middleton and Ashton Youboty, who was signed off the street 10 days ago, are expected to start against the Texans.
The Jaguars (3-7) now have 17 players on IR. Most of the early ones were backups. Recently, it's all been starters. Knighton and Kampman could be next, especially if Jacksonville officially gets eliminated from the postseason race.
Del Rio said he was hopeful Knighton and Kampman would return.
"Just remain hopeful on that," Del Rio said. "We'll see how it goes."
The team signed quarterback Dan LeFevour off Indianapolis' practice squad to take Cox's roster spot.
LeFevour, a sixth-round draft pick by Chicago in 2010, was claimed off waivers by Cincinnati in September 2010 and spent the entire season on the Bengals' 53-man roster. He was inactive for every game as the No. 3 quarterback. LeFevour spent the 2011 preseason with the Bengals before being waived in final cuts. He was signed to the Colts' practice squad on Nov. 9.
"We studied him coming out," Del Rio said. "That's obviously more of a future, develop a guy, as opposed to a guy that's expected to come in and play."