The Mets squandered a chance to widen their lead in the NL East as Austin Kearns hit a three-run homer and Ronnie Belliard drove in three more in the Washington Nationals’ 13–4 victory last night.

New York’s magic number remained at five and its lead in the division dropped to two games over idle Philadelphia. The Mets play the Nationals again today while the Phillies host Atlanta in the opener of a three–game series.

Carlos Delgado had two hits and Moises Alou extended his club-record hitting streak to 28 games with a sixth-inning double for New York, which had won four of five. Alou also committed an error in left that allowed a run to score in the fourth.

Matt Chico (6–9) pitched into the sixth inning and Ryan Langerhans hit a three-run homer in the ninth for Washington, which did New York a favor by beating the Phillies 5–3 on Sunday.

The Mets, coming off a 4–3 road trip, were looking to get off to a fast start on their season-ending, seven-game homestand but couldn’t overcome a sluggish outing by right-hander Mike Pelfrey. The Nationals pushed across two in the fourth and three in the fifth before they chased Pelfrey (3–8) during a two-run sixth. Pelfrey was 3–0 with a 3.31 ERA in his previous three starts but struggled with his control against Washington.

He walked Ryan Zimmerman and Ryan Church with two outs in the fifth, and Kearns followed with a drive to left-center that made it 5–1. It was his 15th homer of the season.

Pelfrey issued two more walks before departing with two outs in the sixth. Joe Smith relieved and allowed Belliard’s two-run double to left-center.

Pelfrey finished with a careerhigh five walks, one intentional. He also hit a batter with a pitch and allowed five hits and seven runs, six earned.

Belliard also hit an RBI double off Guillermo Mota during Washington’s three-run eighth. He is batting .345 (30-for-87) with 15 RBIs this month.

Paul Lo Duca singled home Alou in the sixth, and Chico departed with runners on first and second and one out. Saul Rivera walked pinch-hitter Shawn Green, loading the bases, and Jose Reyes’ runscoring groundout cut it to 7–3.

Rivera then got Luis Castillo to bounce out with two runners on to end the threat. Rivera also worked the seventh before Luis Ayala and Jesus Colome closed it out.

Notes: Mets OF Marlon Anderson’s appeal of his two-game suspension will be heard Wednesday. Anderson was ejected in the ninth inning of a 5–3 loss to Philadelphia on September 15 and threw his batting helmet toward the plate after he reached the dugout. … Nationals RHP Shawn Hill was scratched from his final start of the season and will have operations on his right arm and left shoulder. LHP Mike Bacsik will start tomorrow night against the Mets in place of Hill.