Francisco Alvarez of the Mets will miss more than four months of action due to a career-ending injury.

Francisco Alvarez of the Mets will miss more than four months of action due to a career-ending injury.

Kansas City Royals catcher Salvador Perez offered a bit of news that should calm the nerves of fans after he left Sunday’s loss to the New York Mets with an injury.

Perez was injured in a fourth-inning collision with Mets outfielder Starling Marte and left the Royals’ series finale with a left groin and hip injury. Perez held on to the ball for the final out but was slow to get up as Marte and Royals pitcher Cole Hamels bent over him before a Kansas City athletic trainer arrived.

Perez took to Twitter Monday to ease speculation about his absence from the Royals lineup against the Chicago White Sox.

“Im (sic) back tomorrow ok,” Perez wrote in response to a fan who said he’ll be in Chicago to see the Royals play this week.

With two outs in the sixth on Monday night, the Mets catcher rocketed a low liner into the left-center field gap, hustled out of the box and flew around first base. And the diminutive second-year man’s head-long slide to the inside of the second base bag eluded the tag.

It was the second double and third extra-base hit of the young season for the 22-year-old playing in just his 132nd big league game of his career.

I’m really happy because my swing is very tight,” Alvarez told SNY’s Steve Gelbs before Monday’s game.

Manager Carlos Mendoza isn’t surprised by the catcher’s good start – six hits in 14 at-bats.

“I saw it from spring training and during the offseason, the way he prepared and the way he came into camp,” he said in his pregame news conference. “How hard he works, how invested he is in the pitching staff and how much he cares about the offensive game.

“And it’s good to see not only getting results but the at-bats. You know, this is a guy that [is] taking tough pitches on pitcher’s counts, when he gets behind in counts he gets back on again and gets to the 3-2, and then when he gets his pitch he’s putting good swings on it. And that’s good to see. So, hopefully, he can continue with this streak ‘cause he’s a talented player.

Mendoza looked a prophet: The double came after Alvarez swung through two straight before taking three straight out of the zone to find an offspeed pitch in the middle of the plate for a full count hit.

But Alvarez told Gelbs that even with his good start he feels he has to do better after the Mets’ got swept to open the season, “It’s not what I want.”

“I play the game because I want to win always. And if we’re losing, even if I do good, if I do great, if I do perfect sometimes,” he said, pausing to shake his head, “if we didn’t win I have that [bad] feeling in my heart.”

Unfortunately, Alvarez’s double was one of just five hits for the Mets in the 5-0 defeat to the Detroit Tigers, sending them to the franchise’s first 0-4 start to a season since 2005.