The Yankees will be without one of their most important relievers for multiple months.

Jonathan Loaisiga will have surgery on Tuesday to remove a bone spur in his right elbow, manager Aaron Boone said before the Yankees’ series-opening clash against the Guardians at Yankee Stadium Monday evening.

Loaisiga will be shut down from throwing for three-to-six weeks.

The Yankees are targeting Loaisiga’s return to the majors in August or September, with August being the earliest they expect him to be able to return to the active roster.

Loaisiga has been on the injured list since April 8 with what the team initially described as elbow inflammation.

He had begun playing catch off of flat ground on Wednesday, but felt soreness in the elbow on Thursday, prompting the Yankees to send him for an MRI on Friday.

Friday’s MRI looked “similar” to the one Loaisiga received in early April and prompted the no-throw shutdown, Boone had said on Saturday, although he added that it revealed “nothing structurally alarming” and that Loaisiga would meet with team physician Dr. Chris Ahmad on Monday.

Loaisiga’s visit on Monday with Ahmad seemingly revealed the bone spur and a more serious injury.

“It wasn’t bothering him throwing and then he came in and had the swelling which they think is related to that spur,” Boone said on Monday. “So they gotta get that outta there.”

It’s a major blow for the Yankees, who have been ravaged by injuries in recent weeks.

Loaisiga pitched in three games this year before he was placed on the injured list, recording a 2.70 ERA.

He was used to get critical outs in the seventh and eighth innings in his three appearances, and is the Yankees’ most-trusted high-leverage reliever outside of closer Clay Holmes.

Without Loaisiga, Michael King, Wandy Peralta and Ron Marinaccio have all elevated into bigger roles as late-game, high-leverage options outside of Holmes.

The Yankees’ bullpen has already gotten off to a good start weathering the storm without Loaisiga.

Despite the team’s struggles around the unit, the Yankees’ bullpen owned a 2.93 collective ERA entering play on Monday.

That mark ranks as second-best in MLB, behind the Orioles.

After a career year in 2021 where Loaisiga recorded a 2.17 ERA in 57 games, he regressed last year with a 4.13 ERA in 50 appearances.

Loaisiga improved as the season progressed, however, and after a strong start to 2023 was expected to play a pivotal role in the Yankees’ bullpen.

It’s instead next man up for the Yankees, much like it is for the rest of the roster at the moment.