(Sports Network) - There has to be an eerie feeling in the New York Mets' clubhouse right now, as the team's lead in the National League East has dwindled down to just a half-game. Tonight, New York will try to solve the Washington Nationals in the second test of a four-game series at Nationals Park.

The Mets dropped Monday's opener by a 7-2 score and had its division lead cut to the smallest of margins over the idle Philadelphia Phillies. Starter Pedro Martinez was saddled with the loss for giving up four runs and eight hits in six innings of work, while Duaner Sanchez allowed three runs in relief.

Jose Reyes ended with two RBI while Brian Schneider and Luis Castillo each scored runs for New York, which suffered through a monumental collapse last September. With a comfortable seven-game lead in the division standings and 17 contests left, the Mets went 5-12 and missed the playoffs on the final day of the regular season.

New York, which has dropped two in a row and three of four, will hand the ball to Mike Pelfrey on Tuesday. Pelfrey is winless in his last three starts (0-1) and did not factor in the outcome of a 13-10 win over Washington his last time out on Wednesday. He allowed five runs and eight hits in five frames to remain at 13-9 in 29 starts this season, while his ERA raised to 3.77.

The right-hander is 2-2 over seven career starts against Washington.

Washington will try to play spoiler once again after ending a five-game losing streak with last night's victory over the Mets. Elijah Dukes belted a three- run homer and Lastings Milledge finished 3-for-4 with two runs scored for the Nats, who got a solid outing out of starter John Lannan.

Lannan, who fanned seven batters, permitted just one run and three walks in seven innings for the win.

Taking the ball for the Nationals on Tuesday will be Odalis Perez, who is 1-0 in his previous three starts with back-to-back no-decisions. In Wednesday's 13-10 loss to the Mets, Perez did not record a decision despite giving up seven runs -- six earned -- in just three innings.

The lefty, who is 6-10 in 27 starts in 2008, owns a 5-6 record and a 4.61 earned run average in 20 career games, 13 of which have been starts, against New York.

The Mets are 10-5 against Washington this season and 4-2 at Nationals Park. New York had won the last five matchups in the series before Monday's loss.