PHOENIX -- Through Jarred Kelenic's first 66 MLB games, there have been ups and downs. Moments that have shown he’s still a 22-year-old with limited big league experience, others that have showcased why he was one of the most heralded prospects in baseball entering 2021.

Friday’s game had a little bit of everything for Kelenic, who is already getting a taste of what it’s like to play meaningful games in September for a Mariners team that is trying to make a late push into the postseason. And his brightest moment of the night was one that decided the outcome.

Kelenic delivered a go-ahead RBI single in the 10th inning to lift Seattle to a 6-5 win over Arizona in the series opener at Chase Field. It capped a 2-for-5 performance that also included a two-run homer, his eighth of the season.

The Mariners (73-62) remain four games back of the Red Sox for the second American League Wild Card berth. But they gained a game on the A’s, who are the first team out, three back of Boston.

“It’s super exciting, we’re still trying to get to the playoffs, that’s our main goal, and these games, they all count, so to come out with a ‘W’ tonight was huge,” Kelenic said. “It’s getting me ready for years to come in my career, and if I’m accustomed to situations like that, it can only help me.”

Kelenic’s 412-foot homer to right-center field in the sixth inning gave the Mariners a 5-1 lead. However, the D-backs rallied for four runs in the seventh, a brief hiccup for Seattle’s bullpen after a quality outing by starter Tyler Anderson (three runs allowed in six-plus innings).

It gave Kelenic a chance to be the hero in extras. With runners on the corners and one out in the 10th, he took an 0-1, 97 mph fastball from right-hander Taylor Clarke the opposite way. Kelenic thought it was going to drop fair, and it did -- just barely, dropping down on the white paint in the left-field grass and allowing Kyle Seager to scamper home from third.

“You’ve got to get that ball in play and shorten up your swing a little bit, and he found a way to get it done,” Mariners manager Scott Servais said.

Earlier in the night, there was another learning opportunity for Kelenic. He’s playing in many of these visiting ballparks for the first time and discovering some of the quirks of each. There’s a spacious center field at Chase Field that Kelenic is patrolling this weekend, and he found out just how big it is in the fourth inning.

Nick Ahmed hit a deep drive to lead off the frame, which had Kelenic sprinting back toward the wall. Not wanting to run into the fence, he thought he was closer to it than he was. He nearly made a running grab, but he couldn’t corral the ball, which dropped down and allowed Ahmed to get a triple.

“I’ve got to make that play, there’s no two ways about it. I take full ownership for that one,” Kelenic said. “I was playing in and that ball was hit really well, and I just felt like I was running forever after that ball. And we had talked before the game that on balls that are going to hit off the wall, they bounce like crazy and to always make sure that you play it off the wall. Don’t run up to the wall and then it bounces past you, and then it’s a triple.

“I was running and I thought I had a play on it, which I did, and then I just felt like I was running so long that I was about to run into the fence.”

Of course, Kelenic more than made up for it later by leading the Mariners to their third straight win and their fourth in five games, a stretch in which all but one contest has been decided by only one run.

Even if Seattle comes up short in its postseason pursuit this season, these moments could be huge for Kelenic and other youngsters as the club builds toward long-term, sustained success in the years to come.

“Any experience is good, but especially close ballgames in a playoff race. That’s got to be great for him,” said right fielder Mitch Haniger, who went 3-for-4 with a two-run homer. “They’re learning to just quiet the noise and stay within themselves and just stay on the task at hand. They’ve been doing a good job, and you’re going to continue to see them grow and get better and better.”