Tannehill, the eighth overall pick in the draft, completed 20 of 36 passes for 219 yards in his NFL debut. But he threw three interceptions in a game-turning stretch late in the first half, and the Texans marched to an impressive opening win in what they believe can be a Super Bowl season.
"We were explosive as a team in that period of the second quarter," Texans coach Gary Kubiak said of his defense's six minutes of opportunism.
Defensive end J.J. Watt deflected two passes that resulted in interceptions and also had 1½ sacks. The 6-foot-5 Watt, Houston's first-round draft pick in 2011, missed most of training camp with a dislocated left elbow.
"I know I have long arms," Watt said. "You can't get a sack every play, so you might as well try to bat the ball."
Schaub threw for 266 yards in his first action since fracturing his right foot in Week 10 last year, and Johnson finished with 119 yards receiving. Schaub announced after the game that he had signed a four-year contract extension that will keep him here through the 2016 season.
"I'm excited for it to be done and over with so every ounce of focus and energy can be directed to this season," said Schaub, whose previous contract was due to expire after this season.
Marcus Thigpen returned a punt 72 yards for Miami's touchdown. The Dolphins gained only 275 total yards.
Tannehill was still encouraged.
"I felt like we hurt ourselves more than they really just stopped us," Tannehill said. "That's a good defense. So being able to move the ball on a good defense like that gives us some confidence. Obviously, we have to fix a lot of things and eliminate those turnovers. But I think it gives us a look at what we could be if we played to our full potential."
Referee Don King called a penalty on "Texas" in the first half, drawing laughter from the fans. Otherwise, the replacement officials avoided any major slip-ups in Houston.
The Texans, who've boldly adopted a "Super Bowl or Bust" mantra, came out sluggish. They dropped passes and missed tackles early and trailed 3-0 in the second quarter. The team unfurled a red, white and blue "2011 AFC South Champions" banner before the game, but the impatient fans were already booing after another drive stalled in the second period.
"It wasn't pretty," Schaub said. "Anyone in our locker room can tell you that we can play much better than we did today."
The Texans got the kick-start they needed from their defense, the catalyst for last year's playoff drive.
Pro Bowl cornerback Johnathan Joseph started the flurry of Miami turnovers when he intercepted Tannehill and weaved 36 yards down the sideline. Mike Pouncey shoved Joseph out of bounds for a personal foul, setting up Houston at the Miami 7.
Shayne Graham tied it with a 35-yard field goal. On Miami's next series, Watt deflected Tannehill's pass at the line, and Brian Cushing came down with another interception. Schaub converted a third down with a 24-yard pass to Johnson, and Foster weaved for a 14-yard touchdown to put Houston in front.
Watt swatted Tannehill's next pass and cornerback Kareem Jackson came down with it at the Miami 27. Richard Marshall then was called for pass interference and Foster plowed into the end zone from the 1.
Tannehill handed off on Miami's next play from scrimmage, but that didn't work for the floundering Dolphins, either. Daniel Thomas fumbled and Danieal Manning recovered at the Dolphins 31 with 28 seconds left before halftime. Schaub threw a pinpoint pass to the end zone for Johnson, who outmuscled Sean Smith for a 24-3 halftime lead.
"I liked the way we were able to work through our uneasiness early in the game," Kubiak said, "and be a darn good football team there in the second quarter."
Thomas, Miami's second-leading rusher last season, left with a head injury and did not return. Miami's Joe Philbin, in his NFL head coaching debut, said after the game that he had no new information about Thomas' injury.
Graham added 40- and 19-yard field goals after Thigpen's punt return.
Miami's Reggie Bush rushed for 69 yards on 14 carries for Miami. ... Johnson has 39 career 100-yard receiving games. ... Texans LB Tim Dobbins left with a neck injury. ... The announced attendance was 71,566, the second-largest crowd for a Texans home game. The record crowd is 71,585, set against Pittsburgh last Oct. 2.
The Atlanta Falcons have agreed to a five-year contract extension with wide receiver Julio Jones. Sources say he will receive $71.25 million total, with $47.5 million guaranteed.
Randall Cobb, who took over for Jordy Nelson as the Packers' No. 1 receiver, was injured on the third play in Saturday's 39-26 preseason loss to the Eagles and was examined in the locker room.
Redskins quarterback Kirk Cousins entered with a chance to secure a starting job and exited the same way after going 20-for-27 for 190 yards and a TD in Saturday night's win vs. the Ravens.
Bengals QB Andy Dalton left Saturday's 21-10 preseason win over the Bears as a precaution with a neck injury that appeared to happen on his first and only series of the night.
Buffalo Bills coach Rex Ryan will decide on his starting quarterback Sunday but will not make his decision public, hoping to keep the Indianapolis Colts -- the Bills' Week 1 foe, in the dark.
Baltimore Ravens wide receiver Steve Smith and Washington Redskins cornerback Chris Culliver were ejected with less than a minute left in the first quarter of Saturday night's preseason game.