Coming off their win over the Cardinals the Chargers flew to Oakland-Alameda County Coliseum for an AFC West division rivalry match against the Raiders. In the first quarter the Chargers' offense had problems when after a three-and-out Mike Scifres' punt was blocked by RB Rock Cartwright out of bounds in the end zone for a safety. Then kicker Sebastian Janikowski made a 50-yard field goal. Then Scifres' punt was blocked again and returned by FS Hiram Eugene 5&#160;yards to the endzone for a touchdown. The Chargers then fought back and took the lead with QB Philip Rivers completing a 19-yard TD pass to TE Antonio Gates. Then RB Mike Tolbert got a 4-yard TD run. Then the Chargers trailed with Janikowski making a 30-yard field goal. But they responded and got the lead back with kicker Nate Kaeding making a 43-yard field goal, followed in the third quarter by Rivers making a 41-yard TD pass to WR Malcolm Floyd. The Raiders replied with QB Jason Campbell completing a 1-yard TD pass to TE Zach Miller. Followed in the 4th quarter by Kaeding making a 34-yard field goal. The Chargers fell behind when RB Michael Bush got a 3-yard touchdown run (with a failed 2-point conversion), followed by SS Tyvon Branch recovering a fumble and running 64&#160;yards to the endzone for a touchdown to give the Chargers a loss, for the first time against the Raiders since 2003. With the loss, San Diego fell to 2-3 for the 4th straight season.
Question: How many different players received a touchdown by Philip Rivers before the fourth quarter?
Answer: 2