Former Yankee Alfonso Soriano hit a long two-run homer and Mike O’Connor stymied the Mets for his first major league win, leading the Washington Nationals to a 6-2 victory last night.

Pinch-hitter Damian Jackson also had a two-run shot and new leadoff batter Marlon Byrd got three hits and scored three times to help Washington win for only the second time in 10 games. The Nation als improved to 2-6 against the NL East-leading Mets this season.

Making his second big league start, O’Connor (1-1) allowed only a homer and a single to Paul Lo Duca in seven impressive innings. The 25-year-old left-hander struck out six and walked two.

Mike Stanton and Chad Cordero completed the three-hitter. Carlos Beltran homered against Cordero leading off the ninth.

John Maine (0-1) lost his Mets debut, giving up four runs and six hits in 5 1/3 innings.

Acquired with reliever Jorge Julio in the January trade that sent Kris Benson to Baltimore, the 24-year-old righthander fanned six and issued two walks. He was pitching in place of injured rookie Brian Bannister, whose out with a hamstring strain.

O’Connor was called up from the minors last week to replace right-hander John Patterson, sidelined with a forearm injury. The lanky left-hander was also solid in his major league debut, allowing three runs – none earned – in five innings last Thursday against St. Louis.

O’Connor fanned Beltran, Carlos Delgado, and David Wright in succession in the sixth and seventh. Plate umpire Jeff Nelson then turned toward New York’s dugout and ejected manager Willie Randolph, presumably for arguing the balls and strikes. Randolph was ejected for the first time this season and the second time in his career.

New York had won five of six.

Byrd and Marlon Anderson opened the game with consecutive doubles down the left-field line, putting the Nationals ahead. Lo Duca tied it with a solo shot in the bottom half.

Byrd doubled to right in the third and Soriano drove a 2-2 pitch from Maine an estimated 440 feet down the left-field line and into the second deck, about five rows up. It was Soriano’s eighth home run.

Nick Johnson snapped an 0-for-16 skid with a leadoff single in the sixth and stole second. He moved to third on Ryan Zimmerman’s grounder to the right side and scored on an RBI groundout by pinch-hitter Jose Guillen against reliever Darren Oliver.

Byrd singled with two outs in the seventh. Just after a black cat snuck his way onto the right-field warning track, Jackson connected on Oliver’s next pitch to make it 6-1. It was Jackson’s first career pinch-hit homer.

Julio, much maligned since his arrival in New York, had a successful outing last night after being called out of the bullpen with no one on and one out in the eighth inning. He struck out Zimmerman and Guillen to end the inning, then retired the ninth inning in order on two fly balls and a groundout.