The Chargers led the Texans 7-0 just 15 seconds into the game, and went into halftime with a 21-7 lead. An 80-yard drive right after the break brought the score to 28-7.
Leadership from Matt Schaub and an invigorated defense held the Chargers to just 10 more yards for the rest of the night.
Houston linebacker Brian Cushing returned an interception to score his first career touchdown, which tied the game with 9:30 to play.
Randy Bullock kicked a 41-yard field goal as time expired to win the game 31-28. He missed his first career attempt from 51 yards late in the first half. Bullock was the first kicker drafted by the Texans last year, but missed the entire season due to a groin injury.
"There was no doubt in my mind that we were going to win that game," said Andre Johnson, who had 12 catches for 146 yards. "Even in the third quarter, we didn't come out playing that great, but we got it together and made it happen."