SEATTLE -- The future began checking in at T-Mobile Park on Friday night as a pair of the Mariners’ promising prospects recorded firsts in a 7-4 victory over the Blue Jays.

Rookie center fielder Jake Fraley -- the club’s No. 8 prospect, per MLB Pipeline -- recorded his first Major League hit and scored a run as he made his Seattle debut after breaking in with a road game at Tampa Bay on Wednesday.

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“It feels pretty good,” Fraley said. “It’s good to get it out of the way, because now it’s just go time and I don’t have to worry about that or focus on it. I can go back to playing a normal game of baseball and not trying to get that first hit.”

And 23-year-old southpaw Justus Sheffield -- Seattle’s No. 9 prospect -- made his first MLB start and battled through four innings after a nervous 37-pitch first, winding up with a no-decision in his initial baby step into the rotation.

“It was a long first,” Sheffield said. “Definitely not what I wanted. But I felt good all night, honestly. I threw some good pitches that were pretty close and mixed in and out pretty well. I left some pitches over the plate and mistakes get hit here. It’s a learning curve, but I’m ready to get out there and hopefully it’ll be a better showing next time.”

Those youngsters are two of the key pieces in the Mariners’ rebuilding process and they join shortstop J.P. Crawford, who laced his sixth home run, as reasons for optimism as the club awaits further reinforcements from its rapidly improving farm system.

But while the Mariners are embracing MLB’s “Let the Kids Play” theme, they still have a few veterans chipping in as well. Dee Gordon -- living up to the lightning bolt emoji for the “Flash” nickname on his jersey for the Players’ Weekend opener -- went 3-for-4 with an RBI triple and a run scored, and Kyle Seager continued his torrid August by going 2-for-3 with two walks, two doubles and two RBIs.

• Players' Weekend names

Seattle has won five of its last six -- including three straight against the Blue Jays -- to improve to 55-74. Toronto, which is undertaking a significant youth movement of its own, has lost six in a row and dropped to 52-79.

Sheffield, making his first Major League start, allowed seven hits and three runs over four innings. He barely survived a rocky first frame when he surrendered four hits and a pair of runs before escaping with a bases-loaded strikeout of Brandon Drury.

Sheffield didn’t exactly sail through from there, but he minimized damage enough to keep the game tied at 3 before turning things over to his bullpen after throwing 86 pitches.

“It was not an easy night for Sheff,” Servais said. “First Major League start. But I thought his stuff in the first inning was outstanding. He really had a lot of life on the ball. … He threw a ton of pitches, but did a really good job to give us a chance. I think he learned some things. That’s what we have to do.

“We have to be patient with these guys. It’s going to be a learning process. He certainly has the stuff to get them out in the big leagues. It’s just going to be the consistency and command of his pitches as he goes along.”

Sheffield was hitting 93-96 mph with his fastball, but needs to sharpen his offspeed pitches and command that heater as he advances. After spending much of the season re-establishing himself at Double-A Arkansas, he’s eager to take advantage of the final six weeks of the season.

“I want to go out there and pitch and show them I belong here,” he said. “It’s been a long year for me, a pretty weird year with everything going on. I know I can pitch up here and I just have to show it.”

Fraley singled sharply to right field in his first at-bat in the second, then raced home on Gordon’s triple to right. The 24-year-old looked like he’d be an easy out at home on the aggressive send from third-base coach Chris Prieto, but the relay throw sailed high to catcher Reese McGuire and Fraley slid in safely for his second run in two games.

“Plenty more of those to come,” Servais said. “Again, he’s another guy we need to give time to get adjusted to the new team, new ballpark, new pitching. But I really like what I’ve seen from Jake so far.”

Fraley nearly had a bases-loaded single in the Mariners’ three-run sixth inning as well, but Toronto center fielder Teoscar Hernandez charged in to glove the ball just above the turf for the final out.

“That’s my third ball where I’ve had a hit taken away from me,” Fraley said with a smile. “I had two in Tampa that I hit really well, good defensive plays. But, hey, it’s a tough league. That’s why they’re in the big leagues. They play good defense.”