"Once you put a score on the board, then another, and the defense gets a stop, the big turnover, it just builds," said Schaub, who bounced back from an interception on Houston's first play to pass for 346 yards. "Momentum keeps building, and you can feel that energy, and it's contagious."
After two straight division titles and playoff trips, the Texans have ample experience in handling trouble together. Schaub provided steady leadership, and their vaunted defense held San Diego to 90 yards -- just 7 on the ground -- in the second half.
"There was no doubt in my mind that we were going to win that game," said 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."
Schaub recovered from that tipped interception on the first play to throw three TD passes -- two to tight end Owen Daniels -- in the final game of the NFL's opening weekend.
But Houston's veteran toughness took over: The Texans' powerful defense shut out San Diego over the final 25 minutes, and Schaub engineered the final 36-yard drive to set up Bullock, who coolly nailed his first NFL field goal.
"I expected us to be in a dogfight," Houston coach Gary Kubiak said. "I'm disappointed with the way we played early, but we did not give up. ... We were mature enough to hang in there and get the win, so we have to be mature enough to know that we didn't play very well."
San Diego's fans got a taste of McCoy's inventive offense - and they got an agonizing reminder of last season under fired coach Norv Turner, when the Chargers blew five halftime leads. In last year's lowlight, San Diego blew a 24-0 halftime lead in its last Monday night game against McCoy's Broncos last October.
"You lose this way, and it stings a little more," Rivers said. "It's disappointing we didn't finish the game, because we had control. You've got to play all four quarters."
"The effort was there," McCoy said. "They did a nice job. We just didn't finish it. It comes down to not finishing a football game."
Cushing came up big in his first game since missing most of last season with a knee injury and then signing a six-year, $55.6 million extension last week. Rivers' under-pressure throw was snagged by Cushing, who got up from his diving catch and rumbled into the end zone.
Schaub finally got the Texans in position for Bullock, a fifth-round draft pick last year who missed all of his first season with a groin injury.
The former Lou Groza Award winner at Texas A&M didn't miss, celebrating the kick with his new teammates and a vocal bunch of red-jerseyed fans who took over the sections behind Houston's bench.
"We've just got to keep the pedal down," Mathews said. "You can see we can put up points, and our defense is looking great."
After Brown made a spectacular diving play for a touchdown with 26 seconds left in the first half, Rivers went right back to work after halftime, moving the Chargers 80 yards for a short scoring pass to Royal and a 28-7 lead. The Texans finally responded with a long drive capped by Garrett Graham's TD catch.
Houston got another boost early in the fourth quarter when Thomas got a 10-yard penalty during a field-goal attempt for unnecessary roughness against Houston's center, giving a first down to the Texans on a new rule for this season. Daniels caught his second TD pass on the next play from 9 yards on the next snap, cutting San Diego's lead to seven points with 14:44 to play.
Copyright 2013 by The Associated Press