SEATTLE — Dallas Keuchel returning to form bodes well for the Houston Astros regaining their early season dominance.

Alex Bregman had a tiebreaking two-run double in Houston’s four-run seventh inning and Keuchel pitched effectively into the eighth to lead the Astros to their fifth straight win, 6-2 over the Seattle Mariners on Monday.

Keuchel (12-3) allowed two runs and seven hits in 7 2/3 innings. He struck out five and walked two in his longest outing since May 5. The left-hander started the season 9-0, but was 2-3 with a 5.35 ERA in his seven previous starts since coming off the disabled list on July 28.

“I thought he was really good,” said Astros manager A.J. Hinch. “His ability on the ground was incredible. And even a couple of the hits early that he gave up the run on, the first run on, were ground balls. That’s vintage Dallas. When he’s good, he’s throwing strikes, he’s down in the zone, he challenges them with balls having to be put in play on the ground.”

Yuli Gurriel and Brian McCann had solo homers in the fifth for the Astros, and Josh Reddick added a two-run single in the seventh. Nelson Liriano finished the eighth inning and Ken Giles struck out the side in the ninth.

“You have to give credit to Keuchel, he was really good today,” Mariners manager Scott Servais said. “Fourteen outs on the ground. Double play balls certainly squashed a couple rallies we thought we got going. He’s an accomplished left-handed starter with a good sinker, and he got it done against us.”

After starter Erasmo Ramirez limited the Astros to four hits, including the two homers, through six innings, Houston broke through against the bullpen.

Marwin Gonzalez singled and McCann walked against Marc Rzepcynski (2-1). Nick Vincent came on and Cameron Maybin advanced the runners with a bunt. George Springer was walked intentionally to load the bases and Bregman sliced an opposite-field double down the right-field line.

“They decided to walk Springer,” Bregman said. “He’s been driving the ball. … I was just fortunate enough to put a good swing on the ball and thankful to come through for my teammates.”

Jose Altuve was intentionally to reload the bases. Reddick’s two-out single scored two more runs.

The Astros, who managed just two singles through four innings, erased a 1-0 deficit with two homers in the fifth. Gurriel opened with his 16th, sending a 1-1 pitch over the wall in left. After Gonzalez grounded out, McCann followed with his 14th.

Kyle Seager brought the Mariners even in the sixth with his 20th, a two-out solo shot to center — his sixth consecutive season of 20 or more homers.

First-inning singles by Jean Segura, Nelson Cruz and Seager staked the Mariners to a 1-0 lead.

Houston, which led the AL West by 16 games at the end of July, stumbled a bit through injuries to 11-17 in August, but are perfect so far in September.

Seattle, coming off a three-game sweep of Oakland, entered the day 2 1/2 games behind Minnesota for the second wild card spot.

MARINERS MOVES

Seattle claimed OF Jacob Hannemann and RHP Seth Frankoff off waivers from the Chicago Cubs on Monday. RHP David Phelps (right elbow impingement) was transferred from the 10-day DL to the 60-day DL and LHP Zac Curtis was designated for assignment.

TRAINER’S ROOM

Astros:C Evan Gattis (right wrist soreness) and RHP Michael Feliz (right shoulder discomfort) could come off the DL this weekend at Oakland, Hinch said. … OF Jake Marisnick (groin) could play Tuesday or Wednesday in Seattle.

Mariners: CF Jarrod Dyson (groin) is day to day, Servais said. … RHP Felix Hernandez, on the 10-day DL (right shoulder bursitis),threw a 37-pitch bullpen session Monday. “The bullpen today was much better than it was the last time,” Servais said.

FIERS DROPPED FROM ROTATION

With the acquisition of RHP Justin Verlander and RHP Lance McCullers coming off the disabled list to start Wednesday, his first since July 30, RHP Mike Fiers is the odd man out and will be used out of the bullpen. Fiers, 8-9 with a 4.78 ERA in a team-high 27 starts, is 1-5 in his last eight starts, giving up 10 homers over that span. Fiers has allowed 31 homers, fourth most in the AL. “I know he hasn’t pitched as well as he can in his last five or six starts, there was a good start mixed in there, but he was a pro about it,” Hinch said Monday. “He understood, he’s been in the league a long time, he’s not naive. He said he’d give us his best effort out of the pen.”

UP NEXT

Astros: RHP Verlander (10-8, 3.82) makes his much-anticipated Astros debut. The 34-year-old, who was the 2011 AL Cy Young winner and MVP, was acquired Friday just before the trade deadline. He was 183-114 in 13 seasons with the Detroit Tigers. Verlander is 10-8 in 22 career starts against the Mariners, including 5-5 at Safeco Field.

Mariners: LHP Ariel Miranda (8-6, 4.85 ERA) makes his team-leading 28th start for an injury-ravaged rotation. Miranda, who has won just once in his last 10 starts, has surrendered 35 home runs, most in the majors. In his last start, he was tagged for six runs in 4 1/3 innings, including four homers.