Broncos turn to rookie Tebow at QB as Orton nurses sore ribs

Tebow Time has arrived for the Denver Broncos.

Rookie quarterback Tim Tebow will make his first NFL start Sunday at Oakland after starter Kyle Orton was limited in practice this week because of bruised ribs, NFL Network insider Michael Lombardi reported Saturday, citing a league source.

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A source told NFL Network insider Albert Breer on Saturday night that Orton, who was injured during last Sunday's loss to the Arizona Cardinals, didn't receive treatment after the game, and the problem grew worse during the week. Orton took all the "mental reps" in practices -- one reason why the possibility that he could play was kept alive -- but Tebow received the first-team reps all week.

A Broncos spokesman said Saturday the team didn't have an announcement about its quarterback situation and that Orton was still considered questionable. The Denver Post reported that Orton would travel for the game against the AFC West rival Raiders.

Under now-fired coach Josh McDaniels, the Broncos traded three draft picks last April to move up and select Tebow 25th overall, but he has made just cameo appearances in six games this season. Tebow has run 12 times for 28 yards and three touchdowns, and his only pass went for a 3-yard score to Spencer Larsen during a Week 10 rout of the Kansas City Chiefs.

Orton ranks fourth in the NFL with 3,653 passing yards this season, but the Broncos have struggled with him at quarterback, going 5-18 over his last 23 games as the starter.

The Associated Press contributed to this report.