ST. PETERSBURG — After making his Major League debut unexpectedly early last September, Junior Caminero reported to Spring Training willing to go wherever the Rays sent him. He hoped then to crack Tampa Bay’s Opening Day roster, although he understood as well as anyone that he had jumped straight from Double-A to the Majors and might need a stop in Triple-A.

“But if I go to Triple-A,” he said back in February, “I’m not gonna spend a lot of time there.”

Caminero spent more time there than just about anyone expected, but that time appears to be over. The Rays are expected to call up Caminero, the No. 2 prospect in baseball, ahead of Tuesday’s game against the Astros at Tropicana Field, a source told MLB.com after Tampa Bay’s 6-1 loss to Houston on Monday night.

The club has not officially confirmed or commented on Caminero’s pending promotion. The Rays will have to make a corresponding move on Tuesday to clear a spot for Caminero on their active roster.

The 21-year-old slugger mashed his way to the Majors last year, slashing .324/.384/.591 with 31 homers and 94 RBIs in 117 games for High-A Bowling Green and Double-A Montgomery before the Rays summoned him to help their injury-riddled lineup against left-handed pitching down the stretch.

Caminero hit .235 (8-for-34) with a homer and seven RBIs in seven regular-season games for the Major League club. He earned a spot on the American League Wild Card Series roster but went hitless in two at-bats as the Rays were swept by the Rangers.

After that, it seemed like only a matter of time before he was back in the big leagues. But the team was cautious with his development, and a pair of left quad strains further slowed his return.

“We’re really excited about what we’re seeing. The at-bats since he’s come back [from the injured list] have looked really good. The defense has made progress,” Rays president of baseball operations Erik Neander told 95.3 FM WDAE on Friday. “It’s just a matter of wanting to make sure that, when he comes here, he’s in position to have success — because it is much, much harder to hit here than it is in Triple-A.

“It’s just working really closely with the staff and gathering feedback to make sure that, when his name’s called, ideally it’s something where we can ride with him for a while and we don’t look back and he’s not having to look over his shoulder.”

Caminero hit well for Triple-A Durham, slashing .276/.331/.498 with 13 homers in 53 games this season. He’s been especially hot this month, going 14-for-40 with three homers in his last nine games.

And few players in the Minors, if any, can match Caminero’s raw power at the plate. According to Statcast, among Triple-A hitters, he ranked second behind James Wood in hard-hit rate (56.5 percent) and average exit velocity (93.3 mph) and had the second-hardest-hit ball (117.2 mph exit velocity) behind Jhonkensy Noel.

Caminero is expected to get most of his playing time at third base and could get some at-bats as the Rays’ designated hitter. Neander acknowledged late last month that Caminero profiled best at third base, and the club essentially cleared the way for him by dealing Isaac Paredes to the Cubs for infielder Christopher Morel and two pitching prospects on July 28.

“Bigger picture,” Neander said then, “it does open up more space at Junior’s natural position.”

The Rays have mostly been using José Caballero and Curtis Mead at third since trading Paredes, and it’s worth noting that Caballero was all over the outfield before Monday’s series opener against the Astros. The infielder worked in center field with first-base coach Michael Johns, then shagged fly balls in both corners during batting practice.

“Just trying to be more useful for the team, trying to be ready for anything to come up,” Caballero said. “I don’t want to be out there and standing. I want to do my job and try to help the team in any way possible.”

But Caminero’s greatest strength is his powerful bat, and the Rays could certainly use it.

Monday’s defeat dropped Tampa Bay back to .500 for the MLB-leading 27th time this season, as Taj Bradley gave up six runs in 4 1/3 innings and the offense managed just one run on four hits and one walk while striking out 13 times against Houston starter Framber Valdez and two relievers.

The Rays have lost seven of their past 11 games, and they’ve scored only 31 runs during that stretch. They rank among the league’s worst clubs this season in runs scored (28th, with 461), OPS (25th, at .683) and home runs (26th, with 110).