ST. PETERSBURG -- For all Osleivis Basabe knew, his time in the Majors was supposed to last just one day. The Rays called up the versatile infielder from Triple-A Durham on Aug. 13, planning to give Wander Franco a rare day off and start the well-regarded prospect at shortstop.

Basabe’s stay is going to last longer than he expected, with Franco on indefinite administrative leave, and he’s already making the most of it.

The 22-year-old rookie blasted a grand slam off Daniel Bard for his first Major League home run, capping the Rays’ nine-run explosion in the eighth inning Tuesday night as they quickly turned a one-run deficit into a 12-4 win over the Rockies at Tropicana Field.

After recording his first hit in his MLB debut vs. the Guardians, Basabe said that ball would go to his grandfather, who raised him “kind of like a father.” He got his first home run ball back, too, and already has plans for it. This one will eventually go to his daughter, 3-month-old Adhara, who was there to see her dad’s slam in person.

“When she grows up, I'm going to give it to her,” Basabe said through interpreter Manny Navarro. “It’ll be a long wait, but it’ll be a good wait.”

Basabe said he was surprised he homered in only his eighth big league game, admitting he’s “not really much of a home run hitter.” In 365 Minor League games, he only hit 12 homers, none of them a grand slam. Basabe's bat-to-ball ability and defensive versatility helped make him the Rays’ No. 6 prospect, according to MLB Pipeline, not the power he showed Tuesday night.

“He’s had a lot of good at-bats. He really has. He’s very competitive up there,” manager Kevin Cash said. “He can beat you to all fields. The power is something maybe we haven’t quite seen yet, but he showed it off today.”

In doing so, Basabe became only the third player in franchise history to hit a grand slam for his first career homer, joining Wil Myers (June 22, 2013) and Jorge Velandia (Sept. 25, 2007). Only two other players in the Majors this season have accomplished that feat, both Brewers: Brice Turang on April 3 and Blake Perkins on June 3.

“I don’t think, even if he had dreamed about it, it would have become true. I’m really happy for him,” catcher Christian Bethancourt said. “We know the situation he came in, and he’s stepping up for us. He’s had some really big at-bats, and he’s taking advantage of the opportunity.”

With the win, the Rays (76-51) moved within two games of the division-leading Orioles (77-48) and improved to 14-8 in their past 22 games after going 5-15 from July 1-26, and they’re averaging 6.2 runs per game during this hot stretch compared to 3.3 during their July skid.

“That’s kind of the Rays that we’ve been waiting to see, I guess. As of late, it’s been a lot better,” said starter Zack Littell, who gave up four runs on seven hits in 5 1/3 innings. “Putting together at-bats like that is what you want to see coming down the stretch.”

Basabe played a part in the early stages of the Rays’ rally, reaching on an infield single after Jose Siri began the eighth with a single to center. Curtis Mead walked, then Bethancourt slapped the first pitch he saw to left for a game-tying pinch-hit RBI single off lefty Brent Suter.

Yandy Díaz put the Rays on top with another RBI single, Randy Arozarena added a two-run single off Daniel Bard, then Isaac Paredes kept the inning alive with a two-out RBI double before Siri was hit by a pitch to load the bases for Basabe.

Looking to make better contact than in his previous at-bats, Basabe unloaded on Bard’s 1-2 slider up in the zone and launched it a Statcast-projected 393 feet to left-center field. When he returned to the Rays’ dugout, his teammates might have been even more excited than he was.

They showed it afterward, too, showering him in the clubhouse with beer, baby powder and, as Basabe put it, “everything.”

“We were very happy, and you can’t get any better than that grand slam right there,” Díaz said through Navarro. “He’s demonstrating to everyone what he’s capable of doing. That’s exactly what he’s doing. Thank God he’s up here.”

Eight games into his big league career, Basabe is hitting .303 (10-for-33) with an .846 OPS, three doubles and eight RBIs while starting each game at shortstop. In Franco’s unexpected absence, Basabe has stepped up in a big way -- and hopes to keep doing so, however much longer he’s here.

“Whether I'm here today, tomorrow, whether they send me down here shortly, whatever it is, I'm just here to play a role,” Basabe said through Navarro. “I'm having as much fun [as I can], and hopefully I can still stay up here as long as I can.”