Ryan Clady hasn't missed a game since being selected 12th overall by the Denver Broncos in the 2008 draft, and he's been a key member of an offensive line that has helped quarterback Peyton Manning begin 2013 on a record-setting pace.

That will change Monday night when Denver hosts the Oakland Raiders, who will attempt to contain Manning while playing without one of their top defensive backs.

Clady, a three-time Pro Bowler, signed a five-year extension with $33 million guaranteed in July after allowing one sack as Manning attempted 583 passes last season.

The left tackle, though, has been lost for the season due to a Lisfranc tear in his left foot suffered in Sunday's 41-23 victory over the New York Giants. Chris Clark will start in Clady's place against an Oakland defensive line that is tied for the NFL lead with nine sacks.

"Stepping up into a role like this, it's not going to be hard for me to adjust," Clark said. "It's not about filling a guy's shoes for me. It's about me creating my legacy, just helping the team the best way I can and doing my job."

Clark has made six career starts at tight end but none at tackle. Clark, though, said watching Clady should make it easier for him.

"You try to mimic those things because he's been a great player, and those things will help me a lot," he said.

Clady's injury is another blow to an offensive line that lost center Dan Koppen to an ACL injury during the summer. Manny Ramirez has filled the role nicely, though.

"You want your quarterback to feel comfortable when he's back there, knowing that the person that's responsible for that is going to make the right calls and the right adjustments when the time comes," Ramirez said.

Manning hasn't had to worry about much so far. His 131.0 passer rating leads the league, and he added two touchdown passes Sunday to the NFL record-tying seven he threw as Denver (2-0) beat Baltimore 49-27 in Week 1.

He is the first in NFL history to throw nine touchdowns and no interceptions in the first two weeks of a season. Manning's 307 yards Sunday allowed him to join Dan Marino and Brett Favre as the only players to throw for 60,000 in their careers.

"He's the best of the best," Raiders defensive back Charles Woodson said. "The thing with him is you try your best to give him different looks and not let him know what (defense) you're in. If he knows what you're in, you see what he's done the first couple of weeks."

Making matters worse, Oakland's secondary took a hit when strong safety Tyvon Branch injured his right ankle in a 19-9 win over Jacksonville last week. Coach Dennis Allen, Denver's defensive coordinator in 2011 before leaving to take over the Raiders, said Branch will miss "some time."

Usama Young will be part of the rotation filling the void.

"Having a guy like that in the locker room, on the field, in meeting rooms. It's a devastation," Young said. "As a group, you have to put your best foot forward to go ahead and get the next guy up."

The Broncos' offense is averaging 463.0 yards and 45.0 points, and Sunday would be as good of a time as any for Oakland to force its first turnover of the season.

"We have to get the ball," Woodson said. "Not to have any fumbles, not to have any interceptions has been tough. That's something we've got to start doing. That's especially true against a guy like Peyton Manning."

The Raiders (1-1) feel they have their own threat under center in Terrelle Pryor, who threw for 126 yards and ran for 50 on Sunday after rushing for 112 yards in a 21-17 loss to Indianapolis in Week 1.

Darren McFadden carried 19 times for 129 yards against the Jaguars, but Denver has allowed a league-low 81 rushing yards. Given that stingy defense and an offense that possesses other weapons such as receiver Wes Welker and tight end Julius Thomas (three touchdowns apiece), Allen knows his team will have its hands full.

"This will be the best team that we've faced and they're very talented," Allen said. "We're going to have to do a good job of changing things up and mixing some things up, mixing some looks and be able to play a good, team game."

The Broncos are expecting the return of Pro Bowl cornerback Champ Bailey, who practiced with Denver on Thursday for the first time since hurting his left foot last month. However, the Broncos could be without linebacker Shaun Phillips, the team leader with 2 1/2 sacks, as he's questionable due to back spasms.

Denver has gone 14-1 while Manning has posted a passer rating of 90.5 or better in 15 straight regular-season games, beginning with a 37-6 win over Oakland on Sept. 30. He completed 75.7 percent of his passes with four touchdowns against the Raiders last season, also guiding Denver to a 26-13 win over Oakland on Dec. 6.