NEW YORK -- Tom Glavine knows exactly what he wants to do in his last tuneup for the postseason. He just doesn't know when he's going to get that final start.
"I just want to have better command than I did tonight," he said. "There isn't a whole lot more to work on."
The NL East champions finished 50-31 at Shea Stadium, losing five of their last six. They return home next week for Game 1 of the playoffs.
Glavine (14-7) gave up eight hits and four runs -- three earned -- in six innings. It was his first loss since Aug. 16 and the most hits he has allowed since he surrendered 10 in four innings at Atlanta on July 30.
He is slated to make his final start of the regular season on Saturday at Washington, but manager Willie Randolph said before the game that will depend on how the rest of the staff does this week.
"If something changes, then I'll adjust accordingly," Glavine said. "I certainly wouldn't want to go into the first game of the playoffs on two or three days' rest.
"On the other hand, I wouldn't want this to be my last start and have eight days' rest."
The Mets were encouraged by the return of center fielder Carlos Beltran, who missed the previous six games with a strained quadriceps. He walked three times and grounded out.
Ryan Zimmerman hit a three-run double for the Nationals and Beltran Perez pitched into the seventh inning in his second major league start.
"I couldn't ask for much better than what he did out there," Washington manager Frank Robinson said. "I like what I see with this young man and he's got a good idea about what to do, how to do it and what his strengths and weaknesses are."
Brian Schneider tied a career high with four hits and Jose Vidro went 3-for-3. Washington won three of four for the franchise's first series victory in a four-game set at Shea since the Montreal Expos did it Sept. 18-21, 2003.
Vidro scored on catcher Paul Lo Duca's throwing error in the sixth to make it 4-2 and Bernie Castro added a two-run single in Washington's three-run eighth.
Perez (2-0) walked six and retired the side in order only once but managed to limit New York to two runs and four hits in 6 1/3 innings. He got his first major league win last Tuesday night, allowing one hit in six shutout innings against Atlanta.
"I just tried to stay on top of the ball, keep the ball down so I would be effective," Perez said through a translator.
Cliff Floyd's RBI groundout in the third cut Washington's lead to 3-2 but Perez struck out Shawn Green with a runner on second for the final out. David Wright grounded into an inning-ending double play with two runners on in the fifth.
Green led off the second inning with a home run to put the Mets in front 1-0. Jose Valentin walked with one out and moved to second on Glavine's sacrifice, but Nook Logan made a terrific leaping catch against the wall in center to take a hit away from Jose Reyes.
"What I liked about him was his composure out there on the mound," Robinson said of Perez. "Even after the home run, he came right back and got the next hitter out."
The Nationals rallied in the third, helped by some uncharacteristic wildness by Glavine. Felipe Lopez and Alfonso Soriano walked to load the bases with one out, and Zimmerman doubled into right-center field to give Washington a 3-1 lead.
"Command is an issue," Randolph said. "Balls and strikes were almost even. Tom's a control guy, we know that. Control was an issue but sometimes it escapes you and that's what happened to him tonight."
Glavine threw 57 of his 107 pitches for strikes and fell to 8-3 with a 2.88 ERA in 15 starts at home this season.
"I had good stuff but I had trouble locating when I wanted to," he said.
Vidro walked after Zimmerman's hit and Glavine then got some help from Lo Duca, who threw out a runner trying to steal third for the second consecutive inning. Schneider tried it in the second and Zimmerman was caught the next inning.
Glavine, who was 2-0 in his previous four starts, fanned Schneider for the final out of the third.
- Nationals 1B Nick Johnson, who broke his right leg in a gruesome collision with right fielder Austin Kearns on Saturday, was expected to remain in the hospital overnight Monday while the rest of the team made the trip back to Washington. The Nationals said Johnson had medical clearance to travel but they were concerned about his comfort. Johnson could travel back to Washington in the next couple of days.
- Nationals pitching coach Randy St. Claire (pneumonia) was out of the hospital but stayed at the team hotel during the game. He was expected to travel back to Washington with the team.
- The Nationals completed their road schedule with a 29-52 record.