Task: Question Understanding
Input (English): Passage: Coming off their divisional home win over the Texans, the Titans stayed at home for a Week 14 intraconference duel with the San Diego Chargers. In the first quarter, the Titans went on the attack first as kicker Rob Bironas managed to get a 44-yard field goal for the only score of the half. In the third quarter, the Chargers tied the game with kicker Nate Kaeding getting a 20-yard field goal. Afterwards, Tennessee would regain the lead with rookie RB Chris Brown getting a 7-yard TD run. In the fourth quarter, the Titans increased its lead with RB LenDale White getting a 7-yard TD run. However, San Diego tied the game with QB Philip Rivers completing a 7-yard TD pass to RB LaDainian Tomlinson and a 2-yard TD pass to TE Antonio Gates. In overtime, the Chargers sealed the win with Tomlinson getting a 16-yard TD run. The Titans have lost 4 out their last 5 games since starting the year at 6-2.
Question: How many touchdown passes did Philip Rivers throw in the fourth quarter?
Output (English): number