Chris Flexen had a night of firsts in his Citi Field debut.
The 23-year-old right-hander got his first big league win and hit, and the New York Mets took an early four-run lead against emergency starter A.J. Griffin in a 5-4 victory over the Texas Rangers on Tuesday night that stopped a four-game losing streak.
"It's exciting," Flexen said. "The first win's always the toughest, especially with the first two outings being a little rough."
Michael Conforto, Yoenis Cespedes and Travis d'Arnaud homered for the Mets, who led 4-0 after two innings. Cespedes went deep at Citi Field for just the third time this season, his first since June 17. D'Arnaud hit his first at home this year after nine on the road.
Promoted from Double-A to the major leagues because of injuries in the Mets rotation, Flexen (1-1) allowed three runs and four hits in 5.2 innings with three walks and four strikeouts. He lost at San Diego in his big league debut on July 27 and did not get a decision at Colorado last week.
Flexen said he got "in a little groove there and was able to execute pitches a little better."
He hit a double that bounced to the left-field wall in the fifth for his first hit after an 0-for-3 start at the plate. He had a .267 average with one extra-base hit in six minor league seasons.
Mets manager Terry Colliins said Flexen's slider was working much better than in his previous starts.
"He's one of those guys that's the future here, and so once in a while, you've got to have some patience and you've got to bite the bullet and give them a little chance to get a sense of what it takes to pitch in the big leagues," Collins said. "It was a good win for Chris. He's got a good arm and he's got good stuff."
A.J. Ramos gave up Robinson Chirinos' two-out homer in the ninth, then retired Drew Robinson on a groundout for his 21st save this year, his first since the Mets acquired him from the Miami Marlins.
Joey Gallo and Adrian Beltre also homered for Texas, with Gallo hitting a 457-foot drive.
Texas pitcher Andrew Cashner, the scheduled starter, woke up in his hotel room with a stiff neck and was replaced by Griffin, who had been slated to start Wednesday.
Griffin (5-3) allowed four runs and four hits in five innings. He beat Minnesota last week in his return from a left intercostal strain that had sidelined him since May 26.
Conforto sent his second pitch, a 66 mph curveball, off the facing of the upper deck in right field. Conforto has a career-best 23 homers, including six leading off.
"They're a good hitting team, an aggressive team. I didn't have my best stuff in the first two innings and they capitalized," Griffin said. "I was just battling to keep the game close."
Flexen took a shutout in the fifth, when Gallo hit his 31st homer. Beltre homered in the sixth, and Gallo greeted reliever Erik Goeddel with an RBI double that cut the Rangers' gap to 4-3.
Asdrubal Cabrera boosted New York's lead back to two runs with an RBI double in the seventh against Jason Grilli.
Matt Harvey threw batting practice for the first time since going on the disabled list for a stress injury to his right shoulder on June 15. Harvey threw 25 pitches to Brandon Nimmo.
"I was a little rusty at first but towards the end I was able to get the ball down and finish the pitches the way I wanted to," Harvey said. "I was excited because it's finally fun to throw a baseball again."
Harvey hopes to make a minor league injury rehabilitation start in the next week or so.
"I felt great," he said. "I am on track to get back, hopefully, pretty soon."
Pain in the Neck
Rangers manager Jeff Banister said Cashner called at midday to say he had a stiff neck.
"I woke up this morning, and felt not very good," Cashner said. "They got me in to see a chiropractor this morning and it just hasn't loosened up at all."
Visibly uncomfortable, Cashner said he probably "just slept wrong at the hotel."
New York's Neil Walker made his first big league start at first base, a position he played for the first time Sunday after a double switch. A third baseman when he first came up in 2009, Walker had played second base exclusively since 2011.
Rangers: RHP Keone Kela was placed on the 10-day DL, retroactive to Saturday, with right shoulder soreness. He was on the DL with the same injury from June 30 to July 20. Texas filled his roster spot by selecting the contract of RHP Ricky Rodriguez from Double-A Frisco.
Mets: RF Jay Bruce went 0 for 3 with a walk after missing two games with a stiff neck. ... INF T.J. Rivera has resumed some baseball activity after going on the DL on July 27 for a partial tear in his right elbow.
RHP Rafael Montero (1-7) starts for the Mets in Wednesday's finale of the two-game series and LHP Martin Perez (5-10) for the Rangers.