ST. PETERSBURG -- Ready or not, the Rays are calling up top prospect Taj Bradley to make his Major League debut on Wednesday night against the Red Sox at Tropicana Field.

The Rays recalled Bradley from Triple-A Durham on Tuesday afternoon to make a spot start in place of starter Zach Eflin, who was placed on the 15-day injured list due to lower back tightness. Eflin’s assignment was made retroactive to Saturday, meaning he will be eligible to return on April 23.

With Tampa Bay extending its historic season-opening winning streak to 11 games on Tuesday night, Bradley will be looking to lead the Rays to a 12-0 start -- and tie the franchise's longest winning streak -- in his first big league outing.

Ideally, the Rays would have liked to give the 22-year-old right-hander more time to develop in Triple-A before summoning him to the Majors. But Bradley was lined up to make his third start of the season for Durham on Wednesday, which made him the choice to fill in for Eflin.

Bradley was informed after the Bulls’ game Tuesday afternoon that he was being promoted to The Show.

“It's a rush for any young player, that first time you get called up,” Rays manager Kevin Cash said. “But I know he's got a bunch of guys that will be excited for him here. He's got a bunch of guys excited for him in Durham. And hopefully we can just continue with the hitting that we've done and give him a little bit of support.”

The Rays are expected to send Bradley down after his debut, likely replacing him with a reliever until Eflin’s turn in their rotation comes up again. At that point, they could pivot to Yonny Chirinos or Luis Patiño, who competed during Spring Training for the spot in the rotation that ultimately went to left-hander Josh Fleming.

A fifth-round pick in the 2018 Draft, Bradley worked his way up the Rays’ system and into top prospect territory. He sits atop MLB Pipeline’s list of Tampa Bay’s Top 30 Prospects, and ranks No. 18 overall on the Top 100 list.

• What to expect from Rays' Bradley in the big leagues

Bradley dramatically transformed his body and pitch mix in 2020 and emerged as arguably the best pitcher in the Minors in ‘21, posting a 1.83 ERA with 123 strikeouts over 103 1/3 innings between Single-A Charleston and High-A Bowling Green. His ascent continued last year, as he went from Double-A Montgomery to Durham (with a Futures Game start in between) while recording a 2.57 ERA over 28 starts.

Bradley features a four-pitch mix: four-seam fastball, cutter, changeup and curveball. He threw 55 pitches over two innings in his first start of the season for Durham, then breezed through five innings on 51 pitches his last time out.

“He's got good stuff, good power to his fastball,” Cash said. “A lot to like. And certainly very, very excited for Taj.”

Eflin, who signed a three-year, $40 million free-agent deal over the offseason, said he felt discomfort in his back Saturday morning after pitching six innings in a 9-5 win over the A’s on Friday night. The 29-year-old said he has dealt with a similar issue before and noted that he’s never missed more than one start because of it.

Eflin pushed back his between-starts bullpen session by a day, but said he “kind of reaggravated it a little bit” on Monday and didn’t want to risk pushing it any further this early in the season. He said an MRI on Tuesday morning returned “very clean imaging” on his back, which left him “really not worried about it at all.”

Still, the Rays are at least temporarily without two of their top projected starters: Eflin and Tyler Glasnow, who threw 15 fastballs off the mound Tuesday in his first bullpen session since being sidelined by an early spring left oblique strain.

Cash said he hopes it will be a “minimal” stay on the injured list for Eflin, who was scheduled to meet with a doctor on Tuesday for further evaluation.

“I think the thought is just [to] go ahead and get it taken care of now and focus more on the rest of the season,” Eflin said.