PEORIA, Ariz. -- Robert Perez Jr. already has his Arizona Fall League Home Run Derby invitation secured. But he added to his credentials anyways on Friday.

The Mariners’ No. 21 prospect clubbed his third AFL homer and walked twice in his three plate appearances to help Peoria defeat Salt River, 5-1, in a seven-inning game at Peoria Sports Complex.

In what would end up being a theme for the day, the right-handed slugger quickly got ahead in the count against Rafters right-handed starter Chad Patrick before swinging for the fences on a 2-0 fastball. The ball left his bat at 111 mph and sailed 434 feet away, per Trackman, for a two-run homer and to open the afternoon’s scoring.

“I saw the baseball like a watermelon,” Perez said. “To get ready for that and be prepared for that and then see it [was huge].”

He certainly acted like he knew it was gone right upon contact. Perez slowly walked out of the box after making such loud contact and casually flipped his bat toward the Javelinas dugout as the ball soared over the left-field fence.

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The 22-year-old first baseman is no stranger to showing prodigious power in the desert this autumn. Perez’s last homer for Peoria came on Oct. 14 at Salt River and traveled 448 feet, according to Statcast. That is still the longest Statcast-measured homer of the Fall League -- 12 feet longer than its closest competition -- and will do so for the rest of the 2022 AFL campaign considering there are no games at Salt River Fields (where Statcast is used) remaining.

Following Saturday’s performance, Perez is now hitting .273/.369/.491 with the three homers over 16 AFL games.

The Venezuela native is playing in the desert after a breakout 2022 season in which he set a new career high with 27 dingers -- besting his previous mark of 15 set the previous year -- and finished with a strong .288/.398/.523 line over 127 games at Single-A Modesto and High-A Everett.

Signed for $75,000 in July 2016, Perez had taken some time to develop his pop, even though he had shown good exit velocities in the past. An improved diet and pregame prep work helped take his strength to a new level, and adjustments to his mechanics helped him elevate his batted balls even more, thus giving them better chances to leave the yard. To wit, his groundball rate dropped from 47.9 percent in 2021 to 40.6 percent this summer. As is typical with launch angle, as his line-drive and flyball rates rose, so did his slugging percentage.

“Sometimes, I was trying to pull around the ball, and I was rushing a lot,” Perez said of his previous mechanical setup. “So I was trying to be taller, see the ball out of the pitchers' hands and be more upfront with my hands.”

Though the full list of Home Run Derby participants has yet to be announced, Perez confirmed that he will be participating after sharing his invitation on Instagram earlier this week. The event will be held Saturday, Nov. 5 at Sloan Park in Mesa, giving the Seattle farmhand one more week to prepare for his spot on the big stage.

“I don't want to get too big with my swing because I think if I get too big, I’m going to miss a lot,” Perez said. “Right now, I haven’t changed, but maybe this week, I want to try to work a little bit on that and see what happens.”

Perez left Friday’s game a few outs early after hurting his left shoulder on a nice catch into the seats up the first-base line in the top of the seventh inning. He confirmed to MLB.com that the injury was “nothing crazy” and added that he felt good in a postgame interview, indicating he isn’t expected to miss time with the Javelinas.

Padres No. 18 prospect Tirso Ornelas and Mets infielder Luke Ritter also went deep for Peoria in the win. Mets No. 11 prospect Mike Vasil struck out five and allowed only one hit over three scoreless innings as the Javelinas starter, but struggled with control by walking three.