New York Mets' Asdrubal Cabrera leaves during the first inning...

New York Mets' Asdrubal Cabrera leaves during the first inning of an exhibition spring training baseball game against the St. Louis Cardinals Thursday, March 10, 2016, in Port St. Lucie, Fla. Credit: AP / Jeff Roberson

VIERA, Fla. — The Mets suffered their first major injury of spring training when it was revealed Friday that shortstop Asdrubal Cabrera has a strained patella tendon in his left knee from running the bases on Thursday.

Cabrera, whom the Mets signed in the offseason to a two-year, $18.5-million deal, returned to New York for a platelet-rich plasma (PRP) injection. Cabrera will be “inactive for approximately two weeks,” the Mets said, and then will “return to baseball activity as tolerated.”

The season opener is April 3 in Kansas City. That gives Cab rera a little more than three weeks to avoid starting the season on the disabled list. You do the math.

“He may not be ready for Opening Day,” general manager Sandy Alderson said. “That’s one of the reasons that we have the depth that we have on our roster that we have now. If he’s ready in three or four weeks, [that’s] essentially the first week of the season and we’ll be in pretty good shape.”

Ruben Tejada and Wilmer Flores could fill in for Cabrera. The team did make the World Series with that duo as the primary shortstops in 2015.

But before Cabrera went down, the Mets were looking at trading Tejada and shedding his $3-million salary. They even were considering releasing him during spring training, which would allow them to save five-sixths of his salary.

“We continually analyze where we are and how our roster looks in relation to our injury situation and other considerations,” Alderson said. “So it’s an ongoing process.”

The Mets also are planning on using Flores as an insurance policy for David Wright at third base. Wright has yet to appear in a game as the Mets ease him in because of his spinal stenosis, but he should make his debut “soon,” manager Terry Collins said.

Prospect Matt Reynolds, whom Collins mentioned as another option at short, has been slowed by a hamstring strain. Reynolds hopes to return early next week.

Cabrera was injured when he tagged up from first to second base on a flyball in the first inning on Thursday. He went in standing up after starting to slide and landed awkwardly. He was immediately replaced by Tejada.

Matz wild in second outing

Pitching on three days’ rest in his second start, Steven Matz was charged with three runs in two-plus innings in the Mets’ 9-5 loss to the Nationals. The Long Island lefty threw two scoreless innings despite his own throwing error in the second. He started the third by throwing eight consecutive balls for a pair of walks and allowing a single to load the bases before he was removed. Antonio Bastardo let all three inherited runners score on a pair of singles.

“Just got a little erratic there,” said Matz. “I really wanted to stay in there and work out of that, but got my work in and I’m going to try to build off those pitches there.”

Extra bases

Righthander Rafael Montero was among six players sent down in the first cuts of spring training. Montero allowed five runs in two innings this spring. The others are righthanders Chasen Bradford, Akeel Morris and Paul Seward, lefthander Dario Alvarez and catcher Raywilly Gomez . . . Dilson Herrera (Colombia) and four other Mets minor leaguers will compete in World Baseball Classic qualifying tournaments next week. Herrera will leave Mets camp on Monday for Panama City, Panama.