Ryan Mathews carried the ball 24 times, gaining 125 rushing yards, and Nick Novak connected on five field goals for the Chargers (4-1).
Tebow replaced Kyle Orton in the second half and guided the Broncos on a comeback try, scoring 14 straight points in the fourth quarter to pull within five points.
The Denver signal-caller launched a desperation pass into the end zone for the win with no time remaining, but it fell incomplete.
Tebow tossed for 79 yards and a touchdown and also ran for a score while Willis McGahee gained for 125 yards rushing for the Broncos (1-4).
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