Mets 2, Nationals 0: Jerry Blevins, Matt den Dekker debut

VIERA, Fla. -- Jonathon Niese tossed six scoreless innings and debuting lefty specialist Jerry Blevins struck out Bryce Harper as the New York Mets beat the Washington Nationals, 2-0, on Tuesday in the final matchup between the NL East rivals before Opening Day.

Ruben Tejada contributed an RBI single and John Mayberry Jr. homered, both against left-hander Gio Gonzalez.

Niese -- who revealed he will start the season's fifth game, at Turner Field against the Atlanta Braves on April 11 -- limited the Nats to four hits while striking out three in a 78-pitch effort. He did not issue a walk.

Mets starters have had impeccable control during spring training. Bartolo Colon, Jacob deGrom, Matt Harvey and Niese have combined to walk 10 batters in 68 2/3 Grapefruit League innings.

"They're a staff that doesn't walk many guys," manager Terry Collins said.

Mayberry's long ball gave the Mets a Grapefruit League-leading 38 homers.

The Mets (18-11) have won 12 of their past 15 games.

Blevins and Matt den Dekker, swapped on Monday, each made their debuts for their new clubs.

In the first of many expected matchups this year, Blevins struck out Harper on three pitches in the bottom of the seventh. An inning later, den Dekker -- in his lone at-bat -- had an opposite-field single against left-hander Sean Gilmartin.

"It was a little bit different, being his teammate yesterday," Blevins said about the matchup with Harper. "But baseball's baseball -- competition. When you're on the field, it's 'ready to go.' It was actually pretty natural. It was different running in from that bullpen. That was the only difference."

Asked if he was playing chess with Harper on Tuesday, or saving his preferred pitch sequences for next week's regular-season meeting, Blevins said: "Good question. I'll leave that as a no comment."

Said Collins: "He's going to have to face obviously the real, real good left-handed hitters in this league. And there's a bunch of them."

The Rule 5 pick Gilmartin, expected to stick as a third left-hander in the bullpen, ultimately notched the save with 1 2/3 scoreless innings.

Meanwhile, Niese reiterated he recently adjusted his delivery, after realizing he was striding toward first base with his right leg rather than toward the plate. He estimates he is now stepping a foot further toward the plate than before. It is reducing the stress on his shoulder and limiting fatigue, since he is not throwing as much across his body.

Niese will have one more tune-up for the regular season. He is due to start and pitch one or two innings in Saturday's exhibition game against the Texas Rangers in Arlington. Niese is being placed in Game 5 of the regular season to separate right-handed starters against the Braves.

"I've been working on my mechanics in between starts and in the bullpen," Niese said. "It feels good now. It makes my arm feel a lot stronger, and with a little bit better command as well. I'm striding probably a foot further toward home plate. It's good. I'm using my legs, using my body to do the pitching instead of just trying to muscle it up there with my arm."

What's next: The Mets complete their home spring-training schedule as Colon opposes St. Louis Cardinals right-hander Carlos Martinez at 1:10 p.m. ET on Wednesday at Tradition Field (SNY).