SEATTLE -- It had been 669 days since Mitch Haniger’s last regular-season home run, but based on the way he played all spring, it was merely a matter of time before he left the yard in the 2021 season.

One of the Mariners' best players -- on paper and in the words of many teammates and general manager Jerry Dipoto -- Haniger unloaded a 387-foot moonshot in the seventh inning that landed in Seattle's bullpen and helped lift the club to a series-clinching 4-0 win over the Giants at T-Mobile Park on Saturday night.

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“There's always a little doubt, but I thought I got it -- especially hearing all the news about them changing the balls, you never know now, I guess,” Haniger joked. “I’ve been driving the ball really well, and that one felt good.”

Playing designated hitter to ease into the grind of the regular season, Haniger also doubled to go 2-for-4, putting his three-game slash line at .308/.308/.615. He also feels as healthy as he ever has to begin a season, thanks to extensive rehab focusing more on body movements.

“Adding in those new things really kind of gave me more confidence with my body, because I was really challenging in ways I never had before,” Haniger said. “And bouncing back from those workouts feeling great was just like a mental confidence. I felt confident throughout the offseason doing things I've never done before and feeling good the day after, and then just moving better and knowing my body more.”

Above all, Haniger is happy to satisfy the competitive appetite he's built up after being sidelined so long. Entering this season, he hadn't played since June 2019 due to multiple injuries and surgeries.

“That's kind of irreplaceable when you’re on the [injured list],” Haniger said. “Some guys go to video games to compete or other things, but it's nothing really like standing in the batter's box and playing the outfield in a real big league game. I've been craving that for a while, so it's been really fun to feel that adrenaline rush again and to get back out there and compete.”

Haniger has thrived in the leadoff role since manager Scott Servais moved him there in the fifth game of Spring Training, and the 1-2 punch that he and Ty France pack at the top of the order offers much promise.

France continued to establish himself as a big league force with a solo homer of his own, belting a two-strike offspeed pitch from San Francisco starter Logan Webb 403 feet with an exit velocity of 111.1 mph, per Statcast, for Seattle's first homer of the 2021 season. After posting a 1.135 OPS in Spring Training, France is off to a 3-for-10 start.

Flexen’s strong debut
If Chris Flexen mirrors the outing he put together in his Seattle debut, the Mariners might have unearthed a steal from overseas.

The 26-year-old right-hander, who pitched a full season in the Korea Baseball Organization last year, went all the way to the end of his pitch leash by throwing 94 over five scoreless innings. Flexen struck out six, gave up four hits and overcame a pair of two-out walks to work out of jams in the third and fourth.

“We really want to build him to where it's getting him feeling good and get the confidence rolling as the season goes along,” Servais said. “He hasn't pitched in this league for a while. But it's great to have him back, and he's really excited. He reinvented himself, so to speak, when he went to Korea, and we liked how it all turned out.”

Flexen is stateside again on a two-year, $4.75 million deal. He spent eight years in the Mets’ organization and is now hoping to reinvigorate himself after going 3-11 with an 8.07 ERA and 2.13 WHIP and recording more walks (54) than strikeouts (49) in 27 big league outings from 2017-19.

Asked how his emotions had changed since his last big league win (Aug. 23, 2017), Flexen couldn’t even recall when that game was.

“I don't remember it,” Flexen said. “But to start off the year with the win and for us to be able to start off the year winning a series is pretty awesome.”

The bar so far is only five innings, and it came against a Giants lineup that is good, but not elite. However, the early return from Flexen was impressive.

Graveman K's five in ’21 debut
Kendall Graveman relieved Flexen and looked even more impressive, striking out five over two innings and allowing only one baserunner via a hit batter. Regardless of the situation, Graveman was slated to be one of the first arms out of the bullpen on Saturday after game matchups prevented him from pitching in the first two games, leaving him as Seattle’s last reliever to see action.

Graveman, who was diagnosed with a benign tumor in his neck last year, has thrived since moving to the bullpen in an effort to lessen his workload.

“Just unbelievable,” Servais said. “The stuff was awesome. … Phenomenal. If we continue to get those kind of efforts out of Gravey -- he emptied the tank in that second inning, we knew we were probably going to stretch him a little bit tonight, and he was throwing the ball so well.”

Also notable out of the bullpen: Rafael Montero picked up a four-out save, his first since assuming the closer role after joining the Mariners in an offseason trade with the Rangers.