NEW YORK -- When Sergio Alcántara's ball cleared the fence in right-center, you could almost hear the sigh of relief that came from the D-backs dugout.

Meanwhile, sitting alone in the Citi Field visitor's clubhouse, right-hander Zac Gallen, who had started and thrown four shutout innings, saw it on TV and celebrated.

The homer gave the D-backs a 2-0 lead in what would become a 3-2 win over the Mets, but more than that, it was the big hit that the struggling offense badly needed as it looked to finally get going.

"Offense has been battling," Gallen said. "But this game is tough. We've seen some tough opponents and tough arms. It was a huge hit. He got that ball pretty good. I was in here watching on TV, the only person screaming in here, so it was pretty awesome."

The D-backs came into the game hitting .135, worst in the Majors, with the next closest team, the Twins, at .189.

Of the 18 runs they had scored (second-worst in baseball), 12 had come in the ninth inning or later, with six of those coming in blowouts, in the ninth inning of games that had already gotten out of hand.

In short, they needed a lift in the worst way.

It ended up coming from Alcántara, who was originally signed by the D-backs out of the Dominican Republic in 2012, then traded to the Tigers in the deal that brought J.D. Martinez to Arizona in 2017. When shortstop Nick Ahmed went down with a shoulder injury this spring, the D-backs reacquired Alcántara from the Cubs for cash considerations.

Whatever amount of money the D-backs paid the Cubs, it was worth every penny to them Saturday.

"Serge is somebody that we feel very comfortable with, especially from the left-hand side," D-backs manager Torey Lovullo said. "He can impact the baseball. It was a good matchup for him. He just got some extension and drove the ball out of the ballpark to get us our first couple of runs. It was quite a relief. I felt like the entire dugout took a big exhale and said, 'OK, good. We're in the lead and playing some downhill baseball.'"

Said Alcántara, "I felt super good. I just went up there looking for a pitch to drive. Thankfully I was able to help my team out."

Seth Beer, who led off the seventh with a bloop single to left, was happy to set the table for Alcántara after being the one who delivered a walk-off homer on Opening Day -- which happened to fall on National Beer Day -- against the Padres.

"It was huge," Beer said of Alcántara's hit. "We've spoken about it so many different times, there are going to be certain days, certain guys that get that big hit. Sometimes you get to eat at the table and sometimes you've got to be the table-setter. And for me today it was kind of to be the table-setter. [The homer] was a big deal, and definitely uplifted the team going into the rest of the game."

The D-backs would tack on a run later in the inning when Daulton Varsho blew through third-base coach Tony Perezchica's stop sign to score on Ketel Marte's double down the right-field line.

Nothing has come easy for the D-backs so far this year, so it was no surprise that they didn't just roll through the final two-plus innings Saturday. The Mets made things interesting with a two-run homer from Starling Marte in the eighth.

Closer Mark Melancon set the Mets down in order in the ninth, though, to close things out.