Schaub was 8 of 11 for 92 yards and a touchdown and the Texans got a 24-17 win over the Dolphins.
Schaub played most of the first quarter for Houston (2-0) and got off to a rough start, throwing an interception on his first series and being sacked on third down on the second. He and the offense got going on the next drive, and he found tight end Owen Daniels wide open in the end zone for a 15-yard touchdown play to put Houston up 7-0.
Case Keenum took over after that and was 11 of 18 for 150 yards with a 38-yard touchdown pass. T.J. Yates finished the game, and was 7 of 9 for 84 yards including a 33-yard touchdown throw to Garrett Graham in the third quarter. The solid performance by both players didn't bring any clarity in the battle to backup Schaub.
Texans coach Gary Kubiak said he isn't closer to a decision and he'll continue to evaluate the pair in the upcoming week.
"TJ's solid again, Case makes some really nice throws in there," Kubiak said. "The easy way for me to answer that is to say they're both doing their jobs. They're making it really hard on me, and that's a good thing for our team."
Ryan Tannehill looked sharp, completing 10 of 15 passes for 141 yards and a touchdown in just under a half of work for the Dolphins (1-2).
"I don't think we played as clean as we have to," coach Joe Philbin said. "Offensively, it took us a while to get going. We did some good things, but there's a lot of room for improvement."
Tannehill wanted to use this game to develop chemistry with Wallace, who joined the Dolphins in the offseason after four years in Pittsburgh. He did that, connecting with Wallace three times for 58 yards, including a 9-yard touchdown pass that tied it at 7-7 in the first quarter.
"It was great for us," Tannehill said. "I think our relationship continues to grow; we continue to be more on the same page the more reps we can practice. It was exciting to get a couple of balls to him and hopefully get his ball rolling."
But the offense took a blow when new tight end Dustin Keller sustained what appeared to be a serious right knee injury. Keller's leg bent unnaturally when he was tackled on the right knee by D.J. Swearinger on an incomplete pass Saturday night. He immediately grabbed his right knee and was soon carted off the field.
Philbin said he didn't have a diagnosis on Keller's injury, but Wallace was preparing for the worst.
"It looked pretty bad, and I'm pretty sure he's going to be out for a while," Wallace said, adding that he hadn't heard anything official on Keller's status.
Houston first-round pick receiver DeAndre Hopkins was also injured, leaving in the second quarter with a concussion. Hopkins, the 27th overall pick this year out of Clemson, had two receptions for 22 yards before the injury.
Kubiak said he wasn't sure how Hopkins was injured, but saw him looking disoriented on the field.
"He didn't run the route, didn't get his depth, was just stumbling all over the place," Kubiak said. "So we got him out."
Andre Johnson saw his first action of the preseason and had one reception for 20 yards.
Texans star linebacker Brian Cushing returned Saturday for the first time since a knee injury ended his season in Week 5 last season and played 10 snaps. He had a tackle and came close to a sacking Tannehill, lunging at him and grabbing his midsection before the quarterback wriggled away on Cushing's final play.
"I'm proud of him," Kubiak said. "For him to go out there and get hit on and stuff like that was a big step."
J.J. Watt, last year's defensive player of the year, saw limited action after sitting out in Houston's first preseason game. Houston defensive end Antonio Smith had a good night, finishing with a sack and a tackle for a loss.
Daniel Thomas took a short pass from Tannehill and turned it into a 27-yard gain that got Miami down to the 4-yard line in the second quarter. A 4-yard run by Lamar Miller two plays later tied it at 14-14.
Houston's Randy Bullock, who missed all of last season with a groin injury, gave Houston a 17-14 lead just before halftime with a 46-yard field goal.
Houston safety Shiloh Keo injured his calf and safety Eddie Pleasant injured his knee in the first half and neither returned. ... Jean's 38-yard touchdown reception was the longest catch by a Texan this preseason. ... These teams have seven players combined who played at Texas A&M, led by Tannehill.