Steven Matz delivers outing he and Mets desperately needed

Bryce Harper provided plenty of fireworks in his first visit to Citi Field with the Phillies, but Steven Matz stole the show on Monday night.

Facing the same Phillies team that scored eight runs off of him in the first inning without Matz recording an out in his previous outing, the left-hander looked like a different pitcher, as Matz bounced back and tossed six excellent innings in Monday’s 5-1 win.

It was a stark contrast from the previous time he took the mound and all eight Phillies who came to the plate against Matz reached base and scored.

Matz allowed just one run in his 99-pitch outing Monday and outdueled Jake Arrieta, as the 12-10 Mets moved into a tie atop the NL East with the Phillies, a half-game ahead of the Braves.

“It was kind of everything you would ask for out of a team tonight and they did it in the biggest spot of the year so far,’’ Mickey Callaway said. “To reclaim what we want.”

Matz also got an assist from home-plate umpire Mark Carlson, who ejected Harper in the top of the fourth after the outfielder expressed displeasure following a strikeout earlier in the inning and then yelled from the dugout during teammate Cesar Hernandez’s at-bat.

This, after the small crowd that was left in Queens after the start of the game was delayed by rain for 95 minutes chanted “overrated” at Harper when he whiffed. Rhys Hopkins followed with a solo homer to left-center to slice the Mets’ lead to 2-1.

After Harper was tossed, he bounded onto the field, George Brett-style, and had to be restrained from going after Carlson, with Philadelphia manager Gabe Kapler also in Carlson’s face.

Harper was replaced in the bottom of the inning by Roman Quinn and the Phillies’ lineup was suddenly a lot less dangerous.

Still, Matz didn’t need much help as he got back to the form he showed for most of his first three starts this season.

“I didn’t put too much weight in that last start, to be honest,’’ Matz said. “I was confident I’d be able bounce back and that’s what I did.’’

His manager was ready to throw last week’s horrific first inning away following Monday’s outing.

“He has about a 1.00 ERA outside that one inning,’’ Callaway said. “He kind of picked up where he left off before that last start. Those things just happen. He focused on today and wiped the slate clean. We really needed that out of him.”

Matz retired the first six batters he faced before Hernandez doubled to left-center to start the third.

He soon found himself in trouble in a scoreless game, as Matz then walked Aaron Altherr before Arrieta bunted the runners over. Matz got Andrew McCutchen swinging for the second out before J.T. Realmuto grounded to short, where Luis Guillorme, filling in for the ailing Amed Rosario, made the play. Rosario made a pair of crucial errors in the first inning of Matz’s previous outing.

“That could have gone the other way,’’ Callaway said of that inning.

The Mets took the lead in the bottom of the inning. With Brandon Nimmo on third and one out, Pete Alonso delivered a double down the right-field line on a 2-2 pitch to score Nimmo to give the Mets a 1-0 lead.

“When I got to two strikes with Brandon on third, less than two outs and they’ve got an ace on the mound, I’m in survival mode,’’ Alonso said. “I’m just thankful I got the barrel to that one ball.”

A Wilson Ramos single with two outs made it 2-0.

After the Phillies got a run back on the Hoskins homer, the Mets extended their lead in the fifth when Jeff McNeil hit his first homer of the season. The Mets added two runs in the seventh.

“We’re fighting all year long,’’ Alonso said. “Every game matters. We’re back in first place. Every game we can grab is huge.”