SAN FRANCISCO Tramaine Brock lost his job as the No. 3 cornerback to Nnamdi Asomugha during training camp. It will be more difficult to pry it away from him this time.
Brock returned an interception for a touchdown 90 seconds into Sunday's game, then nearly did the same after grabbing another interception in the second quarter.
The 49ers' defense forced four turnovers in all, sent Texans quarterback Matt Schaub to the bench and came away with their second straight blowout win, this one by a score of 34-3.
That, coupled with a Seahawks loss to the Colts, means the 49ers trail Seattle by one game in the NFC West.
"We got points off all the turnovers, or in Tramaine's case, he scored a touchdown," coach Jim Harbaugh said afterward. "But that was huge, a great way to start the game."
On the third play from scrimmage, Schaub tried to throw to his favorite target, wideout Andre Johnson, who was coming out of the slot. However, Schaub didn't see Brock, who lined up outside, come off his man and break toward Johnson.
Brock slid in front of the receiver, collected the ball and ran into the end zone for an 18-yard score. It was the fourth straight game Schaub has thrown an interception that was returned for a touchdown.
And he nearly threw another 20 minutes later when Brock again jumped in front of Johnson and took off toward the end zone. This time, he was pulled down from behind by the receiver, but the 49ers' offense needed just four plays including a 2-yard touchdown run by Anthony Dixon to convert that turnover into points.
For the second straight week, Colin Kaepernick had a modest outing, completing 6 of 15 passes for 113 yards. Only three 49ers Anquan Boldin, Vernon Davis and Bruce Miller had receptions. More than half of Kaepernick's total came on a 64-yard catch-and-run touchdown by Davis when the tight end pulled away from safety Ed Reed early in the fourth quarter.
The 49ers got another strong performance from the offensive line and Frank Gore, who finished with 81 yards and a touchdown.
Houston defensive end J.J. Watt, the league's reigning defensive MVP, had a typically strong game with three tackles behind the line of scrimmage and three hits on Kaepernick.
The running game, however, took the sting out of Houston's pass rush, and with San Francisco's defense setting up easy scores, Watt became a non-factor.
"As long as we were able to move the chains effectively on the ground, there was no need to air it out," Miller said.
Brock has had the role of No. 3 cornerback, which against passing teams like Houston involves plenty of playing time.
He was in that spot at the beginning of the 2011 season and was leading the league in interceptions before a broken hand knocked him out of the lineup and allowed Chris Culliver to step in.
With Culliver out with an ACL injury over the summer, Brock again was the 49ers' third cornerback.
Another injury, however, gave Asomugha a chance to step into the role, which he kept until suffering a knee injury Sept. 22 against the Colts.
The 49ers must make a decision on Brock and several other cornerbacks between now and March.
He, starter Tarell Brown, Asomugha and Eric Wright will be unrestricted free agents.
Perrish Cox will be a restricted free agent while Carlos Rogers will count more than any other 49ers player against the salary cap.
Brock said he hadn't scored a touchdown since he played at tiny Belhaven University in Mississippi. He also said he might have had some at Mississippi Gulf Coast Community College.
"But they don't compare to an NFL pick-6 at all," he said.
Read Matthew Barrows' blogs at www.sacbee.com/ sf49ers and listen for his reports Tuesdays on ESPN Radio 1320