ST. PETERSBURG -- The Rays made a flurry of roster moves before Monday’s series opener against the Red Sox at Tropicana Field, reinstating second baseman Brandon Lowe from the 10-day injured list but also losing Opening Day starter Zach Eflin to an injury.

Lowe had been on the IL since April 9 due to a right oblique strain. Eflin was placed on the 15-day IL (retroactive to Sunday) due to lower back inflammation. Additionally, Tampa Bay optioned right-hander Manuel Rodríguez to Triple-A Durham and added reliever Richard Lovelady, a lefty the club acquired from the Cubs on Saturday, to the active roster.

Lowe played a pair of Minor League rehab games with Triple-A Durham on Saturday and Sunday and rejoined the Rays to begin a nine-game homestand against the Red Sox, Royals and A’s. But just as Tampa Bay seemed to be getting closer to full strength, with starter Ryan Pepiot (lower left leg contusion) likely to rejoin the rotation on Wednesday, the club put Eflin on the shelf.

Eflin last pitched on Saturday, giving up four runs on nine hits while throwing 75 pitches over six innings in a 5-4 win over the Blue Jays in Toronto. The 30-year-old right-hander said he felt “a little tweak” in his back after throwing a first-pitch sweeper to Danny Jansen, the second-to-last batter he faced.

Eflin said Monday he was “uncomfortable,” but doesn’t expect a long stint on the IL, figuring the discomfort will dissipate by the end of the week. He said his current injury is “pretty similar” to the low back tightness that kept him out for two weeks last April.

“I'm not too worried about it, honestly. It's just one of those things where I just don't think [starting on] Friday's realistic,” Eflin said. “It kind of happened last year, and I felt good after about eight days. So I'm not not thinking it's gonna be too long after that.”

Manager Kevin Cash estimated Eflin will be out between two and four weeks, depending on how he feels after about a week of not throwing.

“No doubt it's unfortunate,” Cash said. “I think this is similar to something he felt last year, and if it is, that's a good sign for us because he kind of bounced right back, came back, we got it cleared up.”

Lowe played only eight games for the Rays to start the season, going 5-for-27 with a home run and four RBIs, before being sidelined. The slugging second baseman, who was limited by injuries each of the past two years, was preparing for a possible pinch-hit appearance on April 9 when he felt something flare up in his oblique.

“The IL is the worst place to be,” Lowe said Monday afternoon. “It's nice to get back.”

Lowe began a Minor League rehab assignment with Triple-A Durham on May 7 and launched two home runs while playing four games. But he was removed on May 10 for precautionary reasons and felt what Cash described as “a little bit” of discomfort after playing the whole game at second base on May 12.

Lowe went home to Nashville, Tenn., on May 13 and was seen by Dr. Ryan Snowden the following day, who had previously worked with Lowe. Lowe was initially diagnosed with a Grade 1 strain but said further imaging revealed a Grade 2 strain in a different part of his oblique. That provided some peace of mind for Lowe as he resumed his rehab stint.

“Obviously, the risk of re-injury is always there for essentially anything ever, which kind of stinks, but he said the chances of it happening are slim,” Lowe said. “The way that the second image looked was very promising. … He's like, 'With all this stuff, the way that you're going, you're gonna be fine. You might feel a little bit of discomfort, but you're ready to go.'”

With that visit showing Lowe could play to tolerance, he resumed his rehab assignment over the weekend and rejoined the Rays on Monday, starting at second base and batting cleanup. Given his injuries and the potential for continued discomfort, Cash said Tampa Bay must be careful and smart with Lowe’s workload while knowing what a difference-maker he can be at the plate when healthy.

“I know Brandon, his mindset, he wanted to be here four or five days ago. I appreciate that. He's probably gonna want to play every single day. I appreciate that as well,” Cash said. “He wants to help us.”