HOUSTON — The game on the line, the Mariners’ season most certainly on the line, Dan Wilson stretched his right leg onto the top step of the visitor’s dugout and leaned forward, eyeing his starting pitcher intently.

At Bryce Miller’s first hint of trouble all night, with two runners in scoring position in the seventh inning and the Mariners desperately trying to protect a tenuous two-run lead, Wilson did not budge.

Miller rewarded his new manager’s faith, striking out the next two batters — Victor Caratini and Jeremy Peña — with his split-fingered fastball, stranding both runners and ending Astros’ only real threat.

Punctuating the most important start of his big-league career, Miller pounded his chest three times and then pointed his right index finger to the sky, lifting up the Mariners’ playoff hopes for at least one more day in a 6-1 victory over the rival Astros before a mostly quiet crowd at Minute Maid Park.

Back here at a place that has haunted them, against a team that has tormented them, the Mariners (81-76) managed to delay the Astros’ clinching of the American League West title.

The Astros (85-72), playing without slugger Yordan Alvarez (knee) on Monday, still lead the Mariners by four games with five games remaining, needing only one win in the next two games against the M’s to win the division yet again.

But that champagne will chill for at least one more day.

Miller was brilliant over seven scoreless innings, and the Mariners pulled within 1.5 games in the AL wild card, with the Tigers, Royals and Twins all idle Monday.

“I’m really happy to be playing with these guys right now,” said Julio Rodriguez, who went 3 for 5 with two singles, a double and two runs driven in. “It’s a really fun stretch, and we’re going to try to make the most out of it.”

A 26-year-old right-hander from New Braunfels, Texas, Miller had about 20 family and friends on hand sitting some 25 rows behind home plate. While warming up pregame, Miller said his back tightened up on him.

“But I knew it was a big game,” he said, “and we needed to win today. So just had to go out and do what I could.”

He was buoyed by seeing in the stands his 86-year-old maternal grandfather, Ted Luce — “Pap-pap,” as his grandson calls him — who was able to watch his grandson pitch in the big leagues for the first time.

“I could see him up there,” Miller said. “He was the only one with the cowboy hat on in the family section.”

Miller grew up working his grandfather’s ranch in Del Rio, Texas on weekends. He’d bale hay, tend to fences, feed the goats and sheep, or whatever else was asked of him.

Bryce’s mom, Denise, says her dad has had some health issues of late — two recent knee replacements and an ailing back. But Pap-pap was able to rise to his feet with the rest of the family to cheer on Bryce late in Monday’s game.

“I almost started crying,” Denise said.

As Miller walked off the mound after those back-to-back strikeouts to end the seventh, he displayed a rare show of emotion himself, pounding his chest and then strutting ever so subtly back to the dugout.

Miller used all seven of his pitches Monday — and all were effective. He threw his splitter 24 times — a pitch he learned last offseason — and got five swings-and-misses with it, most crucially from Caratini and Peña in the seventh.

“I’m at a completely different point this year than I was last year,” the second-year starter said. “The body feels good, my arm feels good. And just knowing whenever I get to the end of games — emptying the tank, making the pitches in the moments to get out of innings — I think I’ve done a good job at that.”

In three career starts at Minute Maid Park, Miller is 2-0 and has allowed just four earned runs in 19.1 innings (1.86 ERA).

In 31 starts this season, he is 12-8 with a 2.94 ERA, best among Mariners starters.

“I’m really happy that he’s on my team, for sure,” Rodriguez said.

With rookie reliever Troy Taylor warming, Wilson briefly considered turning the ball over to the bullpen in the seventh inning. But he chose to stick with Miller.

“Bryce Miller was phenomenal tonight,” Wilson said. “That seventh inning was something pretty spectacular, to see him pull through that … And he really delivered tonight for us in a big stage and a big ballgame and a big point in the season.”

Peña’s infield single in the second inning was the only hit Miller allowed through six innings, retiring 13 in a row entering the seventh.

Cal Raleigh staked the Mariners to a 1-0 lead off Houston starter Hunter Brown in the third inning when he drove in Victor Robles from second base with a two-out broken-bat single. Robles scored just ahead of throw from right fielder Kyle Tucker.

Rodriguez made it 2-0 in the seventh with a sharp two-strike single up the middle, scoring Justin Turner from third base. However, just before J.P. Crawford touched home plate, Dylan Moore was thrown out at third base trying to take an extra bag — wiping away Crawford’s run.

After Miller escaped in the bottom of the seventh, the Mariners added two more runs in each of the final two innings.

Turner’s sac fly in the eighth scored Raleigh and Jorge Polanco’s double drove in Randy Arozarena.

In the ninth, Robles, Rodriguez and Arozarena all doubled to score two more and make it 6-1.

“We’re just focusing on winning one game at a time,” Rodriguez said. “We took care of business today. We’re gonna get a nice, good sleep tonight and just go at it again tomorrow. I feel like that’s kind of the mentality that everybody has over here, and that’s what we’re going to carry on until we know for sure what was going to happen with us.”

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