SEATTLE -- The Mariners’ Mitch Haniger did something unusual in Monday night’s game against the Red Sox at T-Mobile Park.

He had four hits, but that wasn’t it. And he also hit a home run. Nothing unusual there. He’s had 33 this season, after all.

No, this time Seattle’s quiet right fielder cracked a smile as he rounded first base following the home run, his third in three games and the key moment in the Mariners’ 5-4 win that helped pull them one game closer to an American League Wild Card berth.

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“It doesn't happen often, but when it does, it’s big,” Mariners manager Scott Servais said of that smile. “I did see a show of emotion from him today and I thought it was great.”

After making the All-Star team in 2018, Haniger was seriously injured when he fouled a ball off his midsection in 2019, then injured his back during rehab. The dual surgeries cost Haniger all of 2020, but now that he’s back he’s a top candidate for the AL Comeback Player of the Year Award and a significant driver for the Mariners, who are right back in the playoff race with this win.

“That’s up there,” Haniger said when asked if that was the biggest homer of his career. The seventh-inning shot that skirted over the wall in left-center broke open an intense 2-2 game in the seventh inning.

“That’s a big one, especially given the standings and where we’re at,” Haniger said.

The Mariners are two games behind the Red Sox and the Yankees for the second AL Wild Card spot with 18 games to go and two more games in the series. Seattle has won eight of its last 12, while the Red Sox have dropped three of four.

The three runs in the seventh were unearned after Kyle Schwarber misplayed Jake Bauer’s ground ball at first base with two outs. J.P. Crawford followed with a deep infield single and Haniger homered for his fourth hit of the game.

Diego Castillo (4-5) followed six strong innings by starter Logan Gilbert with a 1-2-3 seventh inning that included two strikeouts to earn the win.

Gilbert went six innings, striking out nine to match his career high. He scattered five hits, earning the no-decision, but turning in one of the best outings of his rookie season. He allowed a solo home run to José Iglesias in the third. And Iglesias stung him again with an RBI blooper in the fifth to tie it at 2.

The rest of the time, though, Gilbert was channeling his alter ego, “Walter” -- a nickname given to him by his teammates -- and strutting off the mound after strikeouts.

“That's just the competing side of it and trying to turn into whatever that side of me is,” Gilbert said. “I think that gets the best out of me. When I'm on the mound I want to be aggressive, I want to compete and get after it. I’m not trying to show up anybody out there or anything like that, but I’m just trying to compete and leave it all out there.”

Gilbert finished off the outing with a fastball for a strikeout in the sixth after Servais decided to leave him in during a difficult stretch.

“That's his pitch, and I'd said before the game, when you have not seen Logan Gilbert before, that fastball gets on you,” Servais said. “... His extension down the mound is as far as anybody's in the big leagues, and put on top of that he's throwing 96, 97 mph and it plays like it's 100. When you've never seen it before, it's not comfortable.”

Drew Steckenrider struck out two in the ninth inning for his ninth save after Paul Sewald gave up solo homers to Xander Bogaerts and Rafael Devers in the eighth to cut the lead to one run. It was Seattle’s 31st one-run win. They lead the AL in the category, and those gritty wins have them right in the middle of the playoff race.

“Our guys believe,” Servais said. “They haven't backed off. They’ve believed in what we're doing and in themselves all year long. So I said [during a meeting Monday] there’s no reason to stop right now. They believe we can get it done and they got it done tonight.”