INDIANAPOLIS (AP) -The Indianapolis Colts may have to stop New England's strong running game without Bob Sanders.

The Pro Bowl safety missed Friday's practice after his surgically repaired right knee stiffened, the second straight week he's had a setback.

Sanders practiced last Wednesday but returned the next day with a swollen, sore knee that forced him to miss the rest of the week and the Denver game. He could be facing a similar scenario this week since coach Tony Dungy said it was doubtful Sanders would play.

``Stiff, tight, that's what we expected,'' a dejected Sanders said Friday. ``I've just got to get on a schedule where I practice enough that I can play.''

Sanders had arthroscopic surgery in September and has missed five straight games since a Week 2 victory over Houston. He hoped to be back two weeks ago, but after running said the knee felt ``a little unstable.'' Last week, Sanders said he felt better and Dungy was optimistic he'd be back for the Denver game.

Instead cornerback Marlin Jackson, a first-round draft pick in 2005, took Sanders' spot in the secondary.

After Sanders missed practice Friday, Dungy downgraded Sanders' chances to return even though the injury report listed Sanders as questionable - meaning there was a 50 percent chance he would play.

Sanders' hard hits and strong play in run support, helped the Colts defense make major improvements last season, and he was rewarded with a trip to the Pro Bowl. He had 118 tackles, one interception and broke up four passes in 2005.

Without him, the Colts defense has regressed. Although the Colts (7-0) remain one of the NFL's two unbeaten teams, Indy's run defense has allowed a league-high 168 yards per game including 227 yards last week against Denver.

The Patriots (6-1) have a strong ground game with veteran Corey Dillon and rookie Laurence Maroney, and the Colts were already expecting a hefty dose of power football even before Friday's news.

Defensive tackle Montae Reagor (orbital socket) has already been ruled out for the Patriots game, and wide receiver Brandon Stokley (knee) missed his third straight day of practice and is unlikely to play Sunday.

The injury news wasn't all bad.

Backup safety Matt Giordano and right tackle Ryan Diem also sat out Friday, but Dungy said Diem is likely to start Sunday night even though he hasn't practiced all week because of a strained left biceps.

If Diem cannot play, rookie Charlie Johnson would probably make his first NFL start in one of the Colts' biggest games of the season.

With New England leading the AFC East and the Colts on top of the AFC South, Sunday's game could have implications in the chase for home-field advantage through the playoffs.

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