SEATTLE (AP) — An early offensive punch from Robinson Chirinos, a solid effort by Houston’s bullpen and another baffling play by Seattle’s defense helped the Astros keep rolling.

Chirinos homered to cap a three-run first inning, Houston’s bullpen pitched six shutout innings and the Astros beat the Mariners 4-2 on Monday night for their sixth win in seven games.

Chirinos’ eighth home run capped a first inning in which Seattle’s decision to use Cory Gearrin as an opener backfired. Gearrin (0-2) gave up an RBI triple to Josh Reddick, a run scoring groundout to Yuli Gurriel and Chirinos’ long homer to cap his one inning of work before handing off to Wade LeBlanc.

Chirinos was guessing he’d get a first-pitch fastball and was correct.

“My plan was to swing early. He’s a guy that likes to throw his fastball first pitch and after that he starts to use his slider,” Chirinos said.

Houston tacked on another run in the sixth when Seattle’s defensive problems resurfaced. With runners at the corners and one out, Gurriel hit a grounder to shortstop Dylan Moore. Alex Bregman broke from third to try and score and Moore threw to the plate, but catcher Omar Narvaez had taken several steps up the first base line believing Moore was going to try and turn a double play. The throw was on target and beat Bregman easily, but instead bounced to the backstop as a fielders’ choice and the fourth run for Houston.

Seattle manager Scott Servais said Narvaez was at fault.

“When the ball is hit the first thing you are thinking is it’s a double play, and Dylan actually made the right read. He wasn’t going to be able to turn a double play on that,” Servais said. “He made a very athletic throw to the plate, and Omar just vacated too early. You got to make sure he is committed to going to second before you trail the play to go back it up.”

Houston starter Corbin Martin was pulled after just three innings, but relievers Framber Valez (2-2) and Chris Devenski worked five scoreless innings. Ryan Pressly pitched the ninth for his third save.

Martin has not been able to finish four innings in his last three starts.

“I was falling behind in the count. I wasn’t as aggressive as I needed to be and throwing 30 pitches in the first inning that kind of slows down the rest of my outing,” Martin said.

Seattle got solo home runs from Mallex Smith and Edwin Encarnacion in the third inning, but the Mariners were 0 for 8 with runners in scoring position, leaving runners at either second or third base in each of the first five innings. Jake Marisnick saved a run in the eighth with a diving catch of Moore’s liner to end the inning.

WADE IN RELIEF

LeBlanc threw eight innings, allowing one run and three hits over the final eight innings after replacing Gearrin. It equaled his career-high for innings pitched and set a club record for most innings pitched in a relief appearance, topping Bryan Clark’s 7 2/3 innings in 1982.

In his three starts since coming off the injured list, LeBlanc had not lasted past the fifth inning.

“There were things in the last two or three starts that were trending toward a quality outing,” LeBlanc said.

ROSTER MOVES

Seattle placed RHP Chasen Bradford on the 10-day injured list with a forearm strain and recalled RHP Matt Festa from Triple-A Tacoma. Bradford pitched two innings on Sunday against the Angels but came out of the outing feeling soreness in his arm. Festa will be in his third stint with the Mariners this season having appeared in seven games.

TRAINER’S ROOM

Astros: Houston manager A.J. Hinch said 2B Jose Altuve, OF George Springer and IF Aledmys Diaz all went through an extensive running program before Monday’s game. Altuve and Diaz also did some fielding drills. Hinch was pleased with the progress all three are making and said the club will get a better assessment of their recovery.

Mariners: SS J.P. Crawford (ankle) did fielding drills before Monday’s game and continues to progress faster than expected from his sprained ankle. Manager Scott Servais said there is a chance Crawford could rejoin the team on the next road trip. … Seattle hopes 2B Dee Gordon (wrist) and IF Ryon Healy (back) will be able to go out on rehab assignments toward the end of this week.

UP NEXT

Astros: LHP Wade Miley (5-3) struck out a season-high nine in his last start vs. the Cubs. He’s allowed three runs or less in 11 of 12 starts this season.

Mariners: Seattle has yet to announce its starter for Tuesday’s game.