TORONTO -- The Rays will get a big boost as they wrap up a pivotal five-game, four-day series against the Blue Jays on Thursday afternoon at Rogers Centre.

Left-hander Shane McClanahan is expected to be reinstated from the 15-day injured list to start Tampa Bay’s series finale against Toronto at 3:07 p.m. ET. McClanahan has not pitched for the Rays since Aug. 24, as he was scratched from his Aug. 30 start in Miami moments before first pitch due to a left shoulder impingement.

“I'm happy to be back, but being back now is the most important thing for me,” McClanahan said Wednesday afternoon. “Obviously, I wouldn't want to miss any games in the first place, but I'm glad to come back now.”

It looked like a potentially scary injury at the time, in part due to McClanahan’s emotional reaction in the bullpen when he realized he wouldn’t be able to make his start. But the Rays avoided the worst-case scenario and, in fact, will have missed McClanahan for the minimum 15-day stint on the IL.

“I was very frustrated. Obviously, with the timing, you're not sure if it's season[-ending] or what. Even if it's minor, a little setback can cause trouble down the road,” McClanahan said. “Ultimately, the frustration led to optimism.”

McClanahan will “certainly” have a limited workload in his first start back, manager Kevin Cash said. But the southpaw didn’t need a Minor League rehab start or a full buildup due to how little time he was sidelined.

“I'm excited. We're all excited to get him back,” Cash said. “We'll be very mindful of his workload. But if he's as efficient as he can be, it should give us a good start, and then we can hand it over to the bullpen.”

McClanahan went on the IL on Aug. 31, received a cortisone shot the next day and resumed playing catch on Sept. 4.  The Rays’ ace said he began to feel better a couple of days after the injection, and his quick progression after that showed it.

McClanahan threw a bullpen session early last week, then further tested his arm with a roughly 50-pitch simulated game at Yankee Stadium on Friday. He came out of that session saying he felt “really good.” The day before his return to the mound, he credited the Rays’ athletic training staff for going about his recovery “the right way.”

“I stayed in pretty good shape, kept working out, kept running and tried to put myself in the best possible position to be ready when I got back,” McClanahan said.

McClanahan has been one of the Majors' top starters this season, going 11-5 with a 2.20 ERA, a 0.86 WHIP and 182 strikeouts in 147 1/3 innings over 24 starts. He earned the starting nod for the American League in his first career All-Star Game, and he allowed only four runs in 19 innings over his previous three starts before going on the injured list.

Depending on how the Rays align their rotation the rest of the way, McClanahan should be able to make four more starts before being lined up to pitch in Tampa Bay's first postseason game, assuming the Rays hang on to one of the three AL Wild Card spots.

McClanahan’s return is a welcome bit of good news for an injury-plagued Rays team that put second baseman Brandon Lowe back on the injured list Wednesday and shut down reliever Ryan Thompson for the rest of the season on Thursday.

Tampa Bay hopes Lowe will return before the end of the season, and there’s still a chance rehabbing ace Tyler Glasnow will return this year. The big right-hander pitched 1 1/3 innings in a Minor League rehab start for Triple-A Durham on Wednesday night, and Cash said he has “multiple” rehab outings scheduled with Durham.