Francisco Alvarez to undergo surgery for torn ligament in thumb in Mets’ nightmare

LOS ANGELES — Francisco Alvarez likely won’t resurface with the Mets until at least June after tests revealed he has a torn ligament in his left thumb.

The second-year catcher is scheduled to undergo surgery Tuesday in Southern California to repair the ligament, with Dr. Steven Shin to perform the procedure.

Alvarez told teammates the rehab time is 6-8 weeks, and an independent source confirmed that timetable.

Alvarez departed Friday night’s game in the second inning in visible discomfort after stumbling as he rounded first base.

Alvarez used his hand, with weight on his thumb, to brace himself and kept running to second.

Omar Narvaez, who replaced Alvarez behind the plate on Friday, figures to receive most of the playing time in Alvarez’s absence.

In need of a backup, the Mets selected veteran Tomas Nido from Triple-A Syracuse after placing him on the 40-man roster.

Nido arrived shortly after Saturday’s game began and entered as a defensive replacement in the Mets’ 6-4 victory over the Dodgers.

Alvarez’s offensive potential will be missed the most. In 16 games this season he owned a .236/.288/.364 slash line with one homer and eight RBIs.

The Mets watched Alvarez help carry the team in stretches last season, when he hit 25 homers.

“Guys are going to have to step up,” manager Carlos Mendoza said. “Narvi, Nido, we feel good about them. … We know how much energy [Alvarez] brings and the way he was playing and he was pretty comfortable. But like I always say, ‘Next man up.’ It’s an opportunity here for Nido and Narvaez to step up.”

Narvaez began last season as the Mets’ starting catcher, but an April calf strain sent him to the IL for two months. Upon his return he was relegated to backup duty, with Alvarez blossoming in the starting role.

“[Alvarez] is a real important piece of our team and we all know that he’s a tough kid,” Narvaez said.

Narvaez admitted he’s not happy with his defensive play and is working to address it.

“I still have to clean up some things about my defense, but I think we’re going to get to the same level everybody knows,” Narvaez said.

Asked specifically where he needs to improve, Narvaez pointed to his pitch framing and movements throwing to second base.

Alvarez became the first position player placed on the IL by the Mets this season. Kodai Senga, Tylor Megill and Sean Reid-Foley are among the pitchers rehabbing on the IL.

Pete Alonso said the Mets will miss the total package Alvarez brings as a catcher.

“He’s a phenomenal player, a tremendous worker and he’s taking so many strides forward, not just maturity at the dish, but defensively he has helped out our staff a ton,” Alonso said. “He’s a great competitor, a great personality and he’s always energized and ready to go. We’re going to miss having him out there and I am going to miss having him out there for sure.”