Starling Marte had spent more than a month seeking an extra-base hit, had slipped to No. 6 in the order and could not find a power stroke.

So in this week of Mets magic, of course it was Marte’s big blast that put the club over the top.

Marte’s eighth-inning home run bailed the Mets out in a 5-4, comeback victory over the Guardians on Sunday at Citi Field in the first game of a doubleheader.

The Mets (24-23) won their fourth straight — each win by one run — and moved over .500 because their bats have come alive late in games.

It was Francisco Lindor’s walk-off, 10th-inning single that keyed Friday’s victory and Pete Alonso’s walk-off homer that sparked the Mets in the 10th on Wednesday.

This time, Marte did not wait for extra innings.

After the Mets’ bullpen blew a 3-0 lead in the top of the eighth, Brett Baty walked to put the tying run on base in the bottom of the inning.

Marte, who had not knocked an extra-base hit since April 14, blasted a four-seamer from Trevor Stephan over the right-field wall to set off a celebration for the 39,995 on hand.

In the top of the inning, those 39,995 were stunned when two of the Mets’ best relievers blew the lead.

Tyler Freeman lined a double to right off Adam Ottavino and scored a couple groundouts later. With two outs, Steven Kwan drove a double, and Amed Rosario’s bloop to right scored a second run of the inning.

Manager Buck Showalter turned to David Robertson, whose third pitch of the afternoon turned into a Jose Ramirez home run.

The star third baseman hammered it to center field as a stunned Robertson put his hands on his head.

Robertson bounced back and recorded the final three outs in the ninth to preserve a game that had started with such promise from Max Scherzer.

Scherzer used a different recipe to cook up an encouraging outing in which he threw six scoreless innings, relying more on guile than gas.

Scherzer, whose season has been filled with starts and stops, enjoyed a second straight encouraging start.

Neck spasms forced him to miss a turn two weeks ago, and he has been fending off discomfort below his right scapula that he is determined to pitch through.

The 38-year-old was not quite himself but found a different way to dominate through six innings, the first time he has lasted that long since Opening Day.

Scherzer’s velocity was down several ticks — a four-seamer that averaged 94 mph last year and entered play at 93.3 mph came through at an average of 92.2 mph — but he thrived anyway.

Scherzer instead played up his secondary offerings to keep Cleveland batters off-balance with sliders, curveballs and changeups.

Scherzer, who was pulled after just 86 pitches, allowed just three hits: an infield single from Mike Zunino, who beat out a chopper to Lindor; a Josh Naylor blast off the right-field wall in which Naylor was thrown out trying to stretch it into a double; and a ground single from Kwan that found a hole.

No Guardians reached second base against Scherzer.