As the MLB playoff race heats up, the Tampa Bay Rays will be without their ace.

Starting pitcher Blake Snell will undergo arthroscopic surgery to remove a loose body in his left elbow this weekend, the team announced Thursday. He was placed on the 10-day IL retroactive to Monday.

Snell is expected to miss at least a month and maybe longer, but the team is confident the southpaw will pitch again this season, anticipating a September return.

Snell’s injury comes with Tampa Bay in the depths of a playoff chase — as of Thursday afternoon the Rays trailed the division-leading Yankees by 10 games, but were just one game behind the Oakland Athletics for the second wild card spot. Their pennant aspirations all but died after losing both games of a doubleheader at Yankee Stadium last week. The Rays are 2-7 in their last nine games.

The Rays inked Snell to a five-year, $50 million extension this offseason after his 2018 Cy Young campaign. In 20 starts this season, the 26-year-old is 6-7 with a 4.28 ERA — a sharp decline from his 21-5 record and 1.89 ERA a season ago. This will be Snell’s second stint on the IL this season after he was previously sidelined with a toe injury in April.

The Rays also still await the return of breakout right-hander Tyler Glasnow, who has been sidelined since exiting his May 10 start with a forearm strain. The 25-year-old was 6-1 with a 1.86 ERA through eight starts before his injury. As they hope to resurrect their postseason ambitions, the Rays will be without, at least momentarily, their top two arms.