SAN FRANCISCO -- The nightmare continued Sunday night for Houston Texans quarterback Matt Schaub, and the San Francisco 49ers took full advantage.
Cornerback Tramaine Brock intercepted two Schaub passes and returned one for a touchdown, and the 49ers routed the Texans 34-3 at Candlestick Park.
The Texans lost their third consecutive game and fell to 2-3, their first losing record since 2010. Schaub became the first quarterback since the NFL-AFL merger in 1970 to have an interception returned for a touchdown four games in a row.
Schaub completed 19 of 35 passes for a season-low 173 yards with three interceptions and a passer rating of 32.2. Schaub has nine interceptions for the season.
"We saw some things on film where he saw pressure and he would throw it off his back foot, look to his hot routes," 49ers safety Donte Whitner said of Schaub. "The one that Tramain got to run it back, was pretty much he thought he saw pressure. We were in a coverage and he jumped the route."
Backup quarterback T.J. Yates replaced Schaub with 14:11 left in the game and the Texans trailing 31-3. Yates completed three of five passes for 15 yards.
After the game, Texans coach Gary Kubiak said Schaub was still his starting quarterback.
"Hopefully that's rock bottom tonight," Kubiak said. "I'm trying to help my quarterback work through a very difficult time right now. I'm trying to help a guy I believe a great deal in."
Schaub said he appreciated Kubiak's support.
"A lot of confidence coming from the head coach," Schaub said. "We've been through a lot together and we're going to continue to go through a lot together. I'll fight tooth and nail for him and anyone in this locker room. We've shed a bunch of blood, sweat and tears and we're going to keep fighting. It's a long season. By no means is anything all said and done. We're going to keep fighting and come together."
The 49ers won their second consecutive game after dropping two straight and improved to 3-2, a game behind the Seattle Seahawks in the NFC West standings.
"I think this team is getting its confidence back," 49ers quarterback Colin Kaepernick said.
Brock picked off two passes in the first half, and 301-pound defensive tackle Tony Jerod-Eddie, dropping into coverage, intercepted a Schaub pass late in the third quarter.
Schaub wasted no time making pick-six history. Brock intercepted his first pass and returned 18 yards for a touchdown, giving the 49ers a 7-0 lead 90 seconds into the game.
Lined up in the right slot, Texans wide receiver Andre Johnson ran a quick out, and Schaub tried to hit him on third-and-6 from the 16. Brock left his man and knifed in from the outside on a "trap" coverage, picked off Schaub's pass headed to the end zone.
"We really didn't run trap all week, but we'd run it during training camp," Brock said. "It just came about. (Safety) Eric Reid called trap so we ran with it."
With 49ers nickel corner Nnamdi Asomugha out again due to a knee injury, Brock filled in for the second week in a row and made a strong case to keep the job. He entered the game with two career interceptions and doubled that total while scoring his first NFL touchdown.
Brock's second interception and 13-yard return to the Houston 32 set up San Francisco's third touchdown of the first half.
Frank Gore ran 17 times for 81 yards and a touchdown for the 49ers, Kaepernick was just six-for-15 for a season-low 113 yards and one touchdown, a 64-yard pass to tight end Vernon Davis. Kaepernick gave way to backup Colt McCoy with 6:01 left to play and the 49ers fully in command.
Texans running back Arian Foster carried the ball 21 times for 98 yards.
The 49ers built a 21-0 halftime lead, but Houston trimmed that advantage to 21-3 on Randy Bullock's 41-yard field goal with 12:01 left in the third quarter. San Francisco answered with Phil Dawson's 38-yard field goal with 5:15 remaining in the third, making it 24-3.
Then early in the fourth quarter, Kaepernick hit Davis with a 64-yard touchdown pass, increasing San Francisco's lead to 31-3. After Whitner stripped Texans running back Ben Tate and cornerback Tarrell Brown recovered at the Houston 8, Dawson drilled a 24-yard field goal with 10:46 left.
Brock gave the 49ers a quick 7-0 lead. On their next drive, the 49ers marched 65 yards in 12 plays for a touchdown, Gore powering in from a yard out, to take a 14-0 lead with 1:37 left in the first quarter.
The 49ers capitalized on Brock's second interception to take a 21-0 lead with 5:03 left in the half. This time, Schaub telegraphed a pass along the left sideline to Johnson. Brock tipped the ball into the air, caught it and raced 13 yards to the Houston 32.
Anthony Dixon scored on a 2-yard run.
NOTES: San Francisco DT Ray McDonald suffered a biceps injury and was ruled out midway through the third quarter. ... The 49ers defense already was without two All-Pros, ILB Patrick Willis and OLB Aldon Smith. Willis missed his second consecutive game due to a strained groin. Smith sat out a second game in a row while undergoing rehab in the wake of his arrest last month on suspicion of driving under the influence of alcohol. ... Texans starting RG Brandon Brooks (toe) was inactive. Backup C/G Ben Jones started in his place.