Trying to snap a two-game skid, the Texans flew to Qualcomm Stadium for a Week 8 intraconference game against the San Diego Chargers.  In the first quarter, Houston's recent struggles continued as Chargers QB Philip Rivers completed a 49-yard TD pass to TE Antonio Gates.  Later, a goof-up on special teams led to more points as a high punt snap went into the end zone.  Punter Matt Turk was unable to fall on the ball and San Diego CB Antonio Cromartie managed to recover it for a touchdown.  In the second quarter, the Texans got on the board with kicker Kris Brown nailing a 40-yard field goal.  However, the Chargers continued their beatdown with Rivers and Gates hooking up again on a 31-yard TD pass.  Later, San Diego increased its lead with Cromartie returning an interception 70 yards for a touchdown, along with Rivers completing a 14-yard TD pass to WR Chris Chambers. After a scoreless third quarter, Houston tried to come back, as QB Sage Rosenfels completed a 28-yard TD to TE Joel Dreessen in the fourth quarter.  That was as close to the Chargers as they got. Starting QB Matt Schaub (11/18 for 77 yards and 2 interceptions) left the game in the second quarter with a concussion, after getting a late hit from San Diego CB Drayton Florence.
Question: How many more touchdowns did Rivers throw than Rosenfels?
Answer: 2