HOUSTON — On a night when they scored five runs off All-Star pitcher Lance McCullers, a right-hander who has tied them in knots and shut them down in recent outings, the Mariners still appeared destined for yet another crushing loss at Minute Maid Park — their personal house of horrors and misfortunes.

The Astros, the American League’s best team, looked every bit the part, erasing the Mariners’ leads and crushing their hopes with each opportunity.

But two brilliant defensive plays by shortstop Jean Segura in the bottom of the ninth staved off a seemingly inevitable walkoff victory, and back-to-back solo homers from Kyle Seager and Danny Valencia in the top of the 10th sent the Mariners to a stunning 9-7 victory over the Astros on Monday.

“We’ve certainly played our fair share of tough games here,” Seager said. “I don’t know the numbers but I feel like we’ve been on the wrong side of a lot of them.”

The Mariners are 22-22 at Minute Maid since the Astros joined the AL West, but this was just their fourth win in the past 12 games here.

“It’s nice to win a game like this,” Seager said. “It’s certainly nice to win a game here like this against that team. That’s a really good team over there and we’ve had a lot of battles. We had a lot of fight in us today. We made big pitches when we needed to, Segura made some absolutely unbelievable plays defensively, had a lot of big hits. It was a battle. It was a big win for us.”

The Mariners’ fifth straight win pushed them back to .500 at 47-47 and guaranteed a winning road trip.

“We talked coming out of the break what it was going to take for us to get back to playing the type of baseball we’re capable of,” manager Scott Servais said. “It’s competing every night, have a little swag when you go out there about yourself, and our guys are really competing well right now.”

Of course, given how the game had gone, there was no guarantee that the bottom of the 10th would be simple. Closer Edwin Diaz was pitching in his fourth game in four days — always a dicey proposition.

But the young closer made it look simple despite showing a little fatigue, working a 1-2-3 10th for his 17th save and closing the Mariners’ best win of the season.

“We’ve had some good (wins) but this is probably right there with the (Justin) Verlander game, how we were getting dominated that night and turned it around,” Servais said. “This one as far as a total team effort: every pitcher, every position player that was on the field really left it all out there.”

It was the ninth time this season that the Mariners had a comeback win in the seventh inning or later. Only three teams — the Astros, Dodgers and Rays — have more with 10 each.

“Really, really proud of our guys,” Servais said. “Competing like that, the effort level, just locked in all night. Obviously we know what kind of season the Astros are having, but our competitive edge was there all night. Our team felt like we were going to win the game the whole night and that says a lot about how the guys are carrying themselves, how they’re going about their business right now. It’s fun to watch.”

With all of his setup men having been used while trying to win the game in regulation, Servais turned the ball over to long reliever Yovani Gallardo to start the bottom of the ninth with the score tied at 7-7. Gallardo would either pitch until the Mariners had a lead or until the Astros won.

It looked as if the latter would happen first and quite quickly. Jose Reddick led off the inning with a double to right field. Defeat seemed imminent for the Mariners. But Segura simply wouldn’t allow the winning run to score. He got the first out of the inning with a diving stop, and falling backward he threw to first to get Marwin Gonzalez for the first out.

“The first one was just react to the ball,” he said. “I reacted and I got it, and I got rid of it as quick as I can.”

Seattle intentionally walked Yuli Gurriel, bringing Nori Aoki to the plate. The former Mariner hit a ground ball to Segura, who fired home to get Reddick at the plate.

“That’s what spring training is for, to practice those kinds of plays to be consistent,” Segura said.

The next move was to intentionally walk Brian McCann to load the bases.

Again, the Astros appeared to have the game won when Alex Bregman hit a ground ball deep into the hole at shortstop. It was headed for the outfield as the game-winning hit, but Segura made a lunging, backhanded grab and fired off-balance to second for the force out to end the inning.

“Like a baseball player, I was just trying to catch the baseball,” he said. “I knew the only chance I had was the force at second. It was just ‘go get it.’ It was the last out and if I don’t get it or make an error, they win the game. I tried to make the play as quick as I can.”

Seager started the top of the 10th with a towering blast to right off lefty specialist Sipp. Seager has homered in each of his last three games. Valencia provided some cushion.

“It’s a good sign hitting it off anybody,” Seager said. “It’s a good feeling, period. In the 10th inning I don’t care who it’s off. It worked out well.”