PHOENIX — Slowly, the Mets began flushing what should have been a comfortable lead Friday night.

There was Chasen Shreve allowing one run in the seventh and Trevor May a two-run blast in the eighth. But after Edwin Diaz recorded two outs so easily to begin the ninth the Mets appeared free of peril.

Except, Diaz left a slider over the plate that Daulton Varsho clubbed over the right-field fence. Tie game. Blown save. More questions about the Mets bullpen.

Starling Marte’s speed let everybody off the hook. The Mets outfielder legged out an infield single in the 10th inning that allowed ghost runner Jeff McNeil to score the go-ahead run in a 6-5 victory over the Diamondbacks at Chase Field.

“That’s a good win for the team, to come back in that situation,” Marte said.

Marte was initially called out at first base by umpire Will Little, but the Mets challenged and the play was overturned. McNeil had advanced to third on James McCann’s ground out to second leading off the inning.

“Every extra-inning game is a little bit different,” McCann said. “Tonight it was more, early in the at-bat I am going to see if I can drive him in and once I have two strikes it’s ‘I have to do a job right here and get the runner over.’ ”

Seth Lugo got the final three outs, allowing the Mets to escape with a victory that had seemed in hand following McCann’s two-run homer in the seventh that extended the lead to 5-1.

Shreve allowed one run on two hits in the bottom of the inning and Christian Walker’s two-run homer in the eighth against May was a warning shot the Mets might need more than five runs. Diaz’s blown save was his first of the season.

“I thought I made a good pitch, but when I saw the video I left it right in the middle,” Diaz said, referring to Varsho’s homer. “I threw 14 pitches and on the bad one they got a homer.”

The Mets (11-4) began the night with a 2.10 ERA from their starting pitchers. David Peterson, replacing injured Taijuan Walker for a second straight start, lowered that number to 2.07 and the Mets bullpen held on late.

After pitching four shutout frames against the Phillies in relief, Peterson has allowed just one run over 10 innings in two starts against the D’backs, showing the stuff that led to a notable rookie season in 2020. Last season, Peterson struggled early and then hit the injured list in June, never to return, first with an oblique strain and then a foot fracture.

He was removed on this night after allowing one run on three hits and one walk over 5²/₃ innings.

Brandon Nimmo’s second opposite-field hit in three innings, a single past third base leading off the sixth, led to the Mets snapping a 1-1 tie. Nimmo raced to third, just beating the throw from left field on Marte’s ensuing single against Oliver Perez, and scored on Francisco Lindor’s sacrifice fly. Pete Alonso’s RBI ground out gave the Mets a 3-1 lead.

The Mets tied it 1-1 in the fourth with two well-placed hits against the shift. Nimmo led off the inning with a chop double to left, after the Diamondbacks with two strikes had moved the third baseman to the right side. The ensuing batter, Marte, worked a full-count walk against Zac Gallen and Lindor’s fielder’s choice left runners on the corners with one out. Alonso’s pop up to right landed perfectly in uninhabited territory for an RBI single. Gallen rebounded to retire Eduardo Escobar before Robinson Cano struck out, flailing at two straight curveballs to conclude the inning.

Peterson was late covering first base in the third inning, leading to the Diamondbacks scoring the game’s first run. Pavin Smith doubled off the right-field fence to start the inning. Jose Herrera’s one-out bouncer to the right side drew Alonso far from first base, and McNeil had to wait for Peterson before he could throw. The infield single put runners on the corners and Cooper Hummel’s ground out brought in the run.

Smith ran the D’backs out of the fifth inning by taking off from first base on Varsho’s fly to left with one out. Smith, who had walked, was on his way to third base as the ball returned to the infield.

Gallen struck out seven and allowed two hits over five innings. Last weekend he limited the Mets to two hits over four shutout innings.

Peterson just missed by a smidge in his attempt to complete six innings. With two outs in the sixth, Ketel Marte hit a bloop to center that Nimmo nearly caught on a dive. Marte’s double prompted Showalter to summon Drew Smith, who escaped the inning by striking out Walker after he had walked Matt Davidson.