Broncos QB Kyle Orton sat out practice Friday with an ankle injury and is a game-time decision for Sunday's pivotal game vs. San Diego, according to multiple media outlets.

Broncos head coach Josh McDaniels said Orton, who hasn't practiced all week, will work out before the game before a decision is made on whether backup Chris Simms will start in Orton's place. Simms has practiced with the first-team offense throughout the week.

"If Kyle is completely able to do what we're going to ask him to do in the game plan, and can do it at a level that allows us to be successful, then we could give him an opportunity to play," McDaniels said, according to The Associated Press. "If he's not capable of playing at that level, or doing some of the things that we need him to be able to do, then you go with the guy who practiced.

Simms completed just 3-of-13 passes for 13 yards with no TDs and one interception in relief of the injured Orton last week in a loss at Washington.

The Broncos (6-3) and Chargers are tied for the AFC West lead.