Quarterback Matt Schaub is likely out at least four weeks with a torn MCL. Strong-side linebacker Zac Diles is out for the rest of the season after breaking his left tibia during a special teams drill before Wednesday's practice at Reliant Park. The injury came during a non-contact drill.

Diles will be replaced by Kevin Bentley, who signed with the Texans as a free agent from Seattle.

Diles will undergo surgery and have a rod placed in the leg. Coach Gary Kubiak said rookie Xavier Adibi also figures into the team's plans at linebacker now that Diles is lost for the season.

"I feel terrible for Zac because he was playing so well, but through adversity comes opportunity," Kubiak said.

While Diles flew under the radar during much of the first half of the season, he was responsible for helping keep the defense somewhat respectable. He stopped a lot of plays from getting out of hand. He is a sound tackler, who had a nose for getting to the ball.

Now the Texans will have to rally without him. It will put more pressure on DeMeco Ryans, who is nursing a sore shoulder and a sore ankle. He didn't even practice Wednesday. Bentley is a capable replacement, but his only main experience this season has been on special teams. It will take awhile before he is able to communicate with his fellow linebackers like Diles was.

Bentley joined the Texans after being a backup in Seattle. He lost the starting job competition to Diles in the offseason, but he said he's prepared to prove he can handle the job.

"Pretty much, the last few years, this has been my role," he said. "I've done it in Seattle the last few years, and I'm ready. I don't know what else to tell you besides I'm ready."

Rosenfels is ready, as well. The spotlight on him will be a little brighter Sunday, as he tries to lead the offense against one of the best defenses in the NFL. When Rosenfels has had a week to prepare for his starts, he has fared well in the past. He won four of five starts last season when he replaced Schaub.

Rosenfels said Baltimore poses challenges you don't see from many teams though.

"They probably run every blitz and every coverage that's ever been in the NFL in history from every front," he said. "They don't just stand there and say, 'We're better than you.' They've got great players and they just do it all. It's hard to put a finger on what exactly they're doing sometimes. They're just all over the place and they blitz from everywhere and on top of that, they've got great players. So, it's a great defense and there's a reason why they are number one in the league."

SERIES HISTORY: 3rd meeting. Ravens lead series, 2-0. In the last meeting in 2005, Matt Stover kicked a 38-yard field goal to win the game with six seconds remaining. The Texans lost the game 16-15. All of their points were from K Kris Brown, who tied his career high with five field goals. His final one gave the team a 15-13 lead with 1:08 to play, but it didn't end up being enough for the win.