Answer based on context:

Hoping to rebound from their embarrassing divisional home loss to the Chiefs, the Chargers flew to INVESCO Field at Mile High for a Week 5 divisional duel with the Denver Broncos.  In the first quarter, San Diego got off to a fast start with QB Philip Rivers getting a 2-yard TD run.  Immediately afterwards on the ensuing kickoff, rookie LB Brandon Siler returned a fumble 23 yards for a touchdown.  In the second quarter, the Chargers increased its lead with kicker Nate Kaeding getting a 26-yard field goal.  Afterwards, the Broncos got their only score of the game with kicker Jason Elam getting a 30-yard field goal.  San Diego would end the half with Kaeding nailing 45-yard field goal. In the third quarter, the Chargers continued their offensive revival with Rivers completing a 9-yard TD pass to TE Antonio Gates and a 15-yard TD pass to WR Vincent Jackson.  In the fourth quarter, RB Michael Turner helped San Diego seal their easy victory with a 74-yard TD run. With the win, the Chargers improved to 2-3.  The win also marked San Diego's first back-to-back wins in Denver since '67-'68.

How many touchdown passes did Philip Rivers throw in the third quarter?
2