With Harper walking to the plate as the potential tying run for the Nationals, Mets manager Terry Collins stayed with Matz.
The rookie got Harper to ground out, and New York held on for a 2-0 victory over Washington on Wednesday to take two of three in the series.
"You don't want to come out in that situation," said Matz, who won his seventh straight start. "And for your manager to have faith in you and leave you out and face the greatest hitter in the game right now is pretty awesome."
Matz (7-1 with a 2.36 ERA) allowed four hits and a walk while striking out seven. He only faced Harper once, after the slumping slugger began the day on the bench in what Nationals manager Dusty Baker called a "mental day off."
After allowing seven runs in the first start this season, the hard-throwing left-hander has allowed only six since while compiling a 1.13 ERA during his winning streak.
Matzretired 16 batters in a row before Clint Robinson's two-out single in the eighth on his 100th pitch. Against Harper, he got behind 2-0 for just the second time in the game before throwing a pair of sinkers. Harper chopped the second one to shortstop Matt Reynolds just to the right of second base.
"I think when you have a young player, there's certain situations that you have to challenge them, and that was one of them," Collins said. "If he's going to be a big winner for us and he's going to pitch in big games, he has to learn how to get those guys out in tight situations, and he did."
Matz's dominance is welcome given the recent struggles of Matt Harvey. New York remained a half-game game behind Washington in the NL East.
"I think he thinks he belongs here," Collins said of Matz. "I think he knows he's part of a very, very good pitching staff. We count on him when he goes out there and I think he picks his game up."
David Wright hit his sixth homer of the season in the first inning. and Rene Rivera singled in a run in the seventh. Jeurys Familia allowed singles to Jayson Werth and Murphy starting the ninth, then got three straight outs to remain perfect in 16 save chances.
Tanner Roark (3-4) allowed two runs -- one earned -- over seven innings for Washington. He gave up his second run after Daniel Murphy's error let Matt Reynolds advance to third ahead of Rivera's single.
"I misplayed another ground ball, which just needs to stop happening," Murphy said of his fifth error of the season. "He throws a double-play ball that should've gotten him out of the inning."
Harper is 0 for 10 over his last four games and batting a season-low .245. He's batting .200 since April 18 (20 for 100) and hasn't homered since May 13.
"This is probably the worst period Bryce has gone through," Baker said. "Every time you go through a bad period or a bad stretch, it's the worst time in your whole life, until the next time."
OFF THE MATT
Harvey will remain in the rotation despite allowing five or more runs for a third consecutive start. Collins said Harvey (3-7) showed signs of improvement in his latest outing, despite the end result.
"We saw great movement on his fastball," Collins said. "We saw the velocity up. We saw the tightness of his slider. Those are all things that we haven't seen in his last couple starts."
Mets: SS Asdrubal Cabrera was removed from the lineup after the first pitch because of back spasms. He hopes to return Friday, Collins said.
Nationals: CF Ben Revere was given a day off out of the starting lineup on a day game after a night game. He has started 16 of 19 games for Washington since returning from a right oblique strain in early May.
Mets: RHP Jacob DeGrom (3-1, 3.07) takes the mound Friday as New York hosts the Dodgers and LHP Alex Wood (1-3).
- Home Plate Umpire - D.J. Reyburn
- First Base Umpire - John Hirschbeck
- Second Base Umpire - Bill Welke
- Third Base Umpire - Vic Carapazza