WASHINGTON – Not since early June had Steve Trachsel pitched this well.

Trachsel, the longest-tenured member of the 2006 Mets team, pitched an excellent game yesterday at RFK Stadium, earning a no-decision in the Mets’ 3-1 victory over the Nationals but issuing one of his best performances this season.

The right-hander went 6 2/3 innings, allowing only one run on five hits and a walk. He struck out four – his most since he had four whiffs on July 6 against the Pirates.

“Trachs was really good [yesterday],” Willie Randolph said. “He was very consistent throwing first strikes and staying ahead in the count for the most part.”

Trachsel actually began the game – as Washington starter Tony Armas Jr. did – with three perfect innings. Both pitchers, though, allowed baserunners in the fourth.

For the Mets, Endy Chavez singled to right with one out, though after Carlos Beltran walked, Carlos Delgado grounded out and David Wright flied out. So no Mets scored.

The Nationals, though, only needed one hit to handle that against Trachsel. Alfonso Soriano led off the fourth with his 200th career homer, a shot to left that put the Nats up 1-0.

“[The pitch] might have been a little bit not as up as we wanted. But in that situation, nobody on base, if he fouls that off, it sets up another pitch,” Trachsel said. “So you’ve got to just tip your hat. ‘Cause he’s got sick pop.”

Soriano does, but Trachsel continued to pitch well following the homer. He allowed only one baserunner in each of the next three frames (a walk in the fourth two batters after Soriano homered, a single in the fifth, a double in the sixth). In the seventh inning, though, after Trachsel gave up two singles following two outs, he left the game and was replaced by Royce Ring.

Trachsel, who is still 11-5 for the season, hasn’t been this good since he gave up one run in seven innings versus the Giants on June 4. He did not get a decision that day either, though in each of his seven starts after that game, he earned victories.