Kyle Orton missed a third consecutive practice Friday with a sprained left ankle.

Coach Josh McDaniels says the Denver Broncos quarterback's availability for Sunday's pivotal contest with San Diego will come down to a game-time decision.

Backup Chris Simms again took first-team practice repetitions, as he has all week in the absence of Orton, who was injured during last week's 27-17 loss at Washington.

Simms is in line to make his first start since September 2006, when he suffered a life-threatening spleen injury while with Tampa Bay.

McDaniels says Orton would be put through a workout before Sunday's game and how he performs will determine whether he plays.

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