Coming off their win over the Jets, the Broncos traveled to Qualcomm Stadium for an AFC West rematch with the San Diego Chargers. The Chargers jumped out to a 10-0 lead, with a 53-yard field goal by kicker Nick Novak in the first quarter, followed in the second quarter by a 6-yard touchdown pass from quarterback Philip Rivers to tight end Antonio Gates. The Broncos responded just before halftime, with an 18-yard touchdown pass from quarterback Tim Tebow to wide receiver Eric Decker. The Chargers added to their lead in the third quarter, with a 25-yard field goal by Novak. The Broncos countered just before the end of the third quarter, with a 41-yard field goal by kicker Matt Prater. Novak missed a 48-yard field goal early in the fourth quarter. Trailing 13-10 with just over five minutes remaining in the fourth quarter, the Broncos marched down the field and tied the game with a 24-yard field goal by Prater. The Broncos' defense subdued San Diego's final drive of the fourth quarter, sending the game to overtime. On the Chargers' second possession in overtime, Novak's potential game-winning 53-yard field goal was blocked. However, head coach John Fox had called a timeout prior to the kick. Novak missed the second attempt wide right. The Broncos' third possession in overtime began with 2:31 remaining, and Prater nailed the game-winning 37-yard field goal with 29 seconds left in overtime. With the win, the Broncos swept their AFC West division rivals on the road for the second time in three seasons. Cornerback Cassius Vaughn suffered a broken bone in his leg, and was placed on injured reserve the following day.. In which quarter did the Broncos first score?