NEW YORK -- The Mets’ starting rotation suffered another significant blow this week, when an MRI revealed that Joey Lucchesi has a full UCL tear in his left elbow. A second opinion confirmed the recommendation of Tommy John surgery for Lucchesi, who will undergo that operation on Thursday.

The procedure will sideline Lucchesi for the rest of this year and likely most, if not all, of next season, as well. Tommy John surgery typically requires a rehab period of 12-18 months.

“It’s a big loss for us,” Mets manager Luis Rojas said on Monday. “A talented young kid that I think is just getting better every time he goes out there.”

A day later, Rojas added: “I think this is going to be a time of growth for him. The next thing you know, he’ll be back pitching for us, and he’ll be dealing like he was before he got this prognosis.”

The news hit during the best stretch of Lucchesi’s season, which included a 1.19 ERA over his past five starts. Following his most recent outing, in which he delivered 5 1/3 shutout innings on Friday, Lucchesi complained of left elbow soreness. The Mets subsequently placed him on the injured list and scheduled him for an MRI. Only Monday did team officials learn of the torn ligament -- an injury that almost always requires Tommy John surgery when significant.

Lucchesi sought a second opinion simply to be certain.

“He’s got a full tear, so it was pretty cut-and-dry that he needs TJ,” general manager Zack Scott said.

Overall, Lucchesi was 1-4 with a 4.46 ERA in his first season with the Mets, who acquired him from the Padres in a three-team deal last winter.

Even with a healthy Lucchesi, the Mets were considering upgrading their rotation before the July 30 Trade Deadline, considering they have also played this entire season without Noah Syndergaard (recovery from Tommy John surgery) and Carlos Carrasco (torn right hamstring). With those two and Jordan Yamamoto (right shoulder soreness) all sidelined, a deal for another pitcher now appears more likely than ever. The best starters available could include Kyle Gibson of the Rangers, Jon Gray and Germán Márquez of the Rockies and Luis Castillo of the Reds.

However, the Mets are wary of spending too much prospect capital on a top starting pitcher, considering their desire to build a sustainable winner. In discussing the organization’s plans on Tuesday, Scott indicated the Mets may be far more likely to pursue short-term fixes, at least until they are able to take better stock of their situation.

“We’re going to explore all options,” Scott said. “Obviously, it would be great to add a player who could impact the team, but also, there’s value in finding players who can stabilize the team as well. I think we’ve got a good club with the players that we have, so sometimes the stabilizer is the more prudent thing to do both short-term and long-term.”

In the extremely near future, the Mets, who are in the midst of three doubleheaders in seven days, do not boast many experienced in-house options. Veteran Jerad Eickhoff threw four scoreless innings in a loss Monday against the Braves, while two other starters -- Nick Tropeano and No. 10 prospect Thomas Szapucki -- are on the club’s 40-man roster. A third, No. 21 prospect Tylor Megill, has turned heads with one of the best upper-Minors performances in the organization.

The Mets will need to use some combination of those pitchers, while also relying heavily on their bullpen, to stay afloat as they move closer to the Deadline.

“It’s a challenge once again,” Rojas said. “This is a baseball season. It’s full of challenges. You have it with the injuries. You have it with the ups and downs of some guys throughout the season, and you have it facing the other teams, really good teams that you’re playing. So there’s challenges everywhere. We’re meeting this one right now.”