NEW YORK — Glenn Sherlock, a popular coach who spent three years on the Mets’ staff last decade, is set to return as the team’s new bench coach under manager Buck Showalter. A source confirmed the appointment, which is not yet official. The Mets plan to announce all their staff hirings later this month.

Originally hired to work under Terry Collins in 2017, Sherlock spent one year with Collins and two with Mickey Callaway before the Mets dismissed him following the 2019 season. He had served as the Mets’ first- and third-base coach.

Sherlock has a longstanding relationship with Showalter, having worked on his coaching staffs with the Yankees in 1995 and the D-backs from 1998-2000. It was Showalter who originally brought Sherlock to Arizona, where the latter spent a total of 21 seasons — two as a Minor League coach and 19 on the big league staff. Among other accolades over a nearly four-decade career, Sherlock was Mariano Rivera’s first professional manager with the 1990 Gulf Coast Yankees.

Upon leaving the Mets after 2019, Sherlock spent two seasons as the Pirates’ catching coach. He’ll now reunite with Showalter in Flushing, on a staff that also includes new hitting coach Eric Chavez, first-base coach Wayne Kirby and third-base coach Joey Cora, as well as incumbent pitching coach Jeremy Hefner. The Mets have not confirmed any of those reported hires.

Showalter still must find an assistant hitting coach and a bullpen coach, as well as any other positions the Mets wish to create on his staff.