Matt Prater kicked a 51-yard field goal with 8:34 left in overtime after making a 59-yarder with three seconds remaining in regulation, and the Denver Broncos stunned the visiting Chicago Bears 13-10 on Sunday for their sixth straight victory.

Marion Barber rushed for 108 yards and a touchdown in place of the injured Matt Forte, but his two big mistakes sent Chicago (7-6) to its third straight loss and one game out of NFC wild card position.

Denver (8-5) moved one game ahead of the Oakland Raiders atop the AFC West.

After Tim Tebow threw a 10-yard touchdown pass to Demaryius Thomas with 2:08 remaining to make it 10-7, the Bears seemed to have the game under control when they recovered the onside kick.

Barber, though, inexplicably ran out of bounds on second down to allow the Broncos, who had no timeouts, to get the ball back at their own 19 with 56 seconds left.

Tebow drove Denver to the Chicago 42 before Prater’s kick made Tebow’s sixth second-half comeback of the season – and fifth in the fourth quarter – possible.

The Bears got the ball first in overtime and were driving smartly when Barber fumbled at the Denver 33. The Broncos drove 33 yards on nine plays to set up Prater’s fourth game-ending field goal of the season, including his third in overtime.

Chicago’s Caleb Hanie was 12 of 19 for 115 yards. Tebow was 21 of 40 for 236 yards – setting career highs for completions and attempts – with an interception. The quarterbacks were sacked a combined nine times.

The game’s first points didn’t come until there was 5:19 left in the third quarter when Barber capped a six-play drive, 42-yard drive with a 9-yard run.

The Broncos drove to the Bears’ 11 in the second quarter before Julius Peppers blocked Prater’s 28-yard field goal attempt. The Bears’ deepest penetration in the first half was the Broncos’ 48.