Then they couldn't be stopped.
Tebow rallied the Broncos with two touchdown passes in the final 2:44 of the fourth quarter to force overtime, and Matt Prater's 52-yard field goal gave them an improbable 18-15 victory Sunday over the stunned Miami Dolphins.
The Broncos appeared beaten when they trailed 15-0 with 5:23 left and took over at their 20. At that point Tebow was 4 for 14 for 40 yards.
But Tebow led TD drives of 80 and 56 yards sandwiched around a successful onside kick, and he scored a 2-point conversion standing up with 17 seconds left to tie the game.
In overtime, Denver's D.J. Williams sacked Matt Moore to force a fumble and recovered it at the Miami 36. Three plays later Prater hit the game-winner.
The Broncos (2-4) won for the first time in the eight games they've played on the Dolphins' field. Miami (0-6) extended the NFL's longest losing streak to nine games, leaving the status of embattled coach Tony Sparano even more tenuous.
The Dolphins lost for the 12th time in their past 13 home games.
Tebow made his first start of the year after Denver benched Kyle Orton, and for much of the game the Broncos sputtered. As Tebow walked to the sideline after one series stalled, spectators chanted his name in derision, and Dolphins players gestured to the crowd to keep the jeers coming.
But with the Broncos on the ropes, he led an eight-play touchdown drive that got them back in the game. Matthew Willis' 42-yard reception was the big gain, and Tebow threw a 5-yard scoring pass to Demaryius Thomas with 2:44 left to make the score 15-7.
Then came the onside kick. Miami receiver Marlon Moore leaped to catch the ball but bobbled it and the Broncos' Virgil Green recovered at their 44 with 2:31 left.
Tebow's strike to a diving Daniel Fells gained 28 yards to the 3. Two plays later, Tebow fooled the Dolphins by rolling left and throwing back to the right to Fells, who dived across the goal line for a 3-yard score with 17 seconds left.
Denver still needed a 2-point conversion to stay alive, and Tebow ran up the middle to send the game to overtime.