NEW YORK – Looking to add some “thump” against left-handed pitching, Nationals manager Davey Martinez is deploying his new-look, righty-heavy lineup against the only southpaw starter they are scheduled to face during this three-game series against the Mets.

The most notable addition is Andrés Chaparro serving as the designated hitter in place of Josh Bell and hitting cleanup. Chaparro, who was recalled from Triple-A Rochester yesterday in hopes of being an impact right-handed bat, had two at-bats in last night’s loss after pinch-hitting for Bell in the eighth inning. He knocked a double off left-hander José Castillo into the right-center field in his first major league at-bat since September.

Other notable changes for tonight’s lineup: Amed Rosario is playing third base in place of José Tena and batting second; Riley Adams is catching in place of Keibert Ruiz; and Jacob Young is in center field instead of Robert Hassell III.

So what is Martinez looking for in those right-handed at-bats against David Peterson, who is the owner of a 2.80 ERA and 1.259 WHIP?

“Just work good at-bats,” the skipper said. “Chaparro, as you saw yesterday, he faced a lefty yesterday, he stayed on the ball and hit the ball well to right-center field. So I'm expecting kind of the same thing today. Just kind of stay on the ball and get some good swings off.”

While Chaparro did see game action Tuesday, was there any thought of easing him into the lineup after only 15 Triple-A games instead of batting him fourth right away?

“He's used to hitting in the middle lineup,” Martinez said. “We're looking for some thump in the middle of our lineup against left-handed pitching. So why not put him in?”

Peterson has given up a .257/.332/.374 slash line and .706 OPS to right-handed hitters this season. And 21 of the 25 walks he has issued have been to righties. So while the Nats’ right-handed hitters will want to be aggressive against him, they also must be patient and accept their walks if he can’t find the zone.

* Derek Law threw his first simulated game against live hitters today, per Martinez. The right-handed reliever, who is recovering from right forearm inflammation, threw 25 pitches, topped out at 93 mph, and mixed in his slider and changeup.

Paul DeJong was among the hitters who faced Law after taking live BP for the first time yesterday. While recovering from a fractured nose after being hit in the face with a fastball on April 15, DeJong has been able to take swings in the cage and has added the face protector flap to his batting helmet.

More to come on those two fronts tomorrow.

* Mason Thompson is throwing at the Nationals’ spring training complex in West Palm Beach, Fla. Martinez said they will give the right-hander, who is returning from last year’s Tommy John surgery, another outing down there before possibly sending him out on a minor league rehab assignment.

“I know he threw the other day and threw the ball well,” Martinez said. “I think we're giving him one more outing down in Florida. And then from there, we'll see where he goes.”

Orlando Ribalta, also in Florida, has started playing catch while rehabbing a right biceps strain, but he hasn’t yet done anything else significant, per Martinez.