HOUSTON -- Having failed to meet lofty preseason expectations as a defensive unit and specifically with the pass rush, the Houston Texans found Sunday a tonic in the form of the Tennessee Titans' porous offensive line.

Texans defensive end J.J. Watt and linebacker Whitney Mercilus combined for six sacks of Titans quarterback Zach Mettenberger and Houston proved relentless in dominating the Titans 20-6 at NRG Stadium.

Mercilus finished with a career-high 3 1/2 sacks, four tackles for loss and four quarterback hits filling in for Jadeveon Clowney (back). Watt added 2 1/2 sacks plus a career-high-tying nine hits on Mettenberger.

The Texans (3-5) limited the Titans (1-6) to 211 total yards, with Mettenberger passing for 171 yards while being sacked seven times.

"It's my job to take advantage when I get them (one-on-one matchups) because I don't get them very often," Watt said. "That's the type of defense we expect to have every week."

The Texans weren't exactly explosive offensively, mustering two short Nick Novak field goals after Titans turnovers yielded prime field position. But quarterback Brian Hoyer delivered two scoring passes, including a 21-yard strike to wide receiver DeAndre Hopkins on the third snap of the second quarter and a 42-yarder to receiver Nate Washington for a 17-6 lead with 3:38 left in the third.

Hoyer finished with 235 passing yards while completing 23 of 35 attempts. Sunday marked the first game without backup quarterback Ryan Mallett, who was released Tuesday, and running back Arian Foster, who suffered a season-ending Achilles injury last week at Miami.

"Whatever it took today," Texans coach Bill O'Brien said. "We had to get the win. It wasn't pretty, but who cares?

"We won the game. We came up with enough points. The defense played well. We did what we had to do."

Houston matched its franchise record for sacks in a game against an offense that entered the weekend having allowed 21 sacks in six games. Only four teams had surrendered more sacks, with Seattle (31), Cleveland and Kansas City (26 each) and San Francisco (25) having already played seven games each.

"They created some one-on-one matchups and they won," Titans coach Ken Whisenhunt said. "We tried a bunch of different things to try to counter that, but we lost matchups.

"We slid the line, we doubled the guys, we chipped. What you have is a balance of trying to do things and trying to get guys out in a pattern, and because of what they were doing coverage-wise it made it difficult."

The Titans committed to the ground game before halftime, attempting just 11 first-half passes. But as the deficit swelled, they opened up the offense out of necessity, paving the way for the Texans to seize upon Mettenberger, who tossed an interception with Tennessee mounting a promising drive as the third quarter came to a close.

The Titans finished with 125 passing yards. And despite averaging a respectable 4.3 yards per attempt, Tennessee was unable to make an impact with its ground attack.

"We were running the ball pretty well the whole game, but yeah, when you get down it's a tough spot to be in," Mettenberger said. "You've got to score points quick especially with the clock against you.

"We did a pretty good job of trying to stick to the game plan as long as possible, but there at the end when you're down two scores, you've got to get points on the board to make it a game. Wish we could have run the ball a little more today, but that's just not the scenario we were given."

NOTES: After going 3-of-4 for 22 yards on the opening drive, Titans QB Zach Mettenberger attempted only seven passes the remainder of the first half, completing three for 11 yards. Mettenberger tossed two critical interceptions last week against the Falcons. ... Texans rookie CB Kevin Johnson had his first career interception on the first play of the fourth quarter. ... With his 21-yard touchdown reception in the second quarter, Texans WR DeAndre Hopkins set a franchise record for career receiving yards through his first three seasons with 2,822. ... Texans OLB Jadeveon Clowney (back) was in and out of the lineup throughout the first half. ... Texans S Kurtis Drummond forced a fumble by Titans KR Bishop Sankey in the second quarter but suffered a concussion on the play and did not return. ... Texans LT Duane Brown departed with a concussion in the third quarter. ... Titans WR Kendall Wright injured his left knee in the third quarter and did not return.