HOUSTON -- The Rangers used an “opener” for the first time this season, and Jesse Chavez retired the Astros in order in the first inning on Saturday night.

The Rangers’ problem was their short-handed bullpen didn’t have Chavez available later in the game, when left-hander Drew Smyly faltered at the end of his outing. Instead, manager Chris Woodward tried to keep this one close with rookies Kyle Dowdy and Wei-Chieh Huang and veteran Jeanmar Gómez.

That didn’t work out as well as the “opener” concept, and the Astros pulled away to an 11-4 victory over the Rangers at Minute Maid Park. The Rangers have lost three straight to the Astros with the final of the four-game series scheduled for Sunday afternoon.

“It's a huge game,” Woodward said. “I think every game is huge, but tomorrow especially. You don't want to come out of here 0-4.”

Astros starter Gerrit Cole dominated the Rangers for six innings, allowing only a home run to Hunter Pence while striking out 12. It was a complete turnaround from his last start against the Rangers a few weeks ago in Arlington, where he allowed nine runs in 4 1/3 innings.

Pence’s home run came off a 99.3 mph fastball. He’s hit 218 home runs since 2008, and Cole’s pitch was the fastest offering he has ever hit for a home run.

The Astros were only up 2-1 going into the bottom of the sixth. The Rangers still had a winnable game in front of them until it all started unraveling for Smyly. Up to that point, he had allowed two runs (one earned) in four innings of work and was hanging tough against Cole.

“I loved the way Smyly threw,” Woodward said. “Obviously, Chavez did a great job.”

Smyly walked Carlos Correa with one out in the sixth, and that’s when the game started to turn. Yuli Gurriel flied out, then Smyly walked Tyler White and Robinson Chirinos -- the Astros’ No. 7 and 8 hitters -- to load the bases.

“Got two quick outs and then just walked the bases loaded,” Smyly said. “It kind of changed the whole game. It was a pretty tight game until then. I’ve got to do better. There’s no excuse. Thought a couple of the pitches were pretty close, didn’t get the call. Next thing you know, walked all three and that’s kind of where it all went south.”

Woodward brought in Dowdy to face Aledmys Diaz, the Astros' second baseman playing in place of the injured Jose Altuve (left hamstring strain). Diaz, who hit 18 home runs for the Blue Jays last season, knocked an 0-1 pitch over the left-field wall for a grand slam.

“That’s a tough situation, bases loaded and two outs,” Woodward said. “I thought it was the right pitch. He didn’t execute. It was middle-middle. He’s going to learn to execute in those situations. I don’t think he’s scared of it, he just needs to execute.”

Ronald Guzmán hit a three-run home run off of Astros reliever Chris Devenski in the seventh to make it a 6-4 game. But the Astros scored three more off Dowdy and Gomez in the seventh, and two against Huang in the eighth.

The Rangers are without Shawn Kelley, who is on the injured list, and that leaves Chris Martin as the closer. Those two and Chavez were supposed to be the Rangers top setup relievers behind José Leclerc . But that was before Leclerc started struggling at the end of games, and the Rangers had to scramble to get their bullpen in order.

The other choices to keep it close on Saturday night were rookie left-hander Brett Martin and second-year right-hander Ariel Jurado.

“We don't really have a choice,” Woodward said. “We have to put guys in these situations. We can't pitch the same guys every day, obviously, and I have complete faith in these guys. I want to put them in these situations. I want to see how they respond. I want to challenge every one of our guys, especially our younger guys. We're going to see what they're made of. And it's not always about the results.”