WASHINGTON -- The last thing rookie Danny Espinosa expected five games into his major-league career was to take a curtain call.
"To have this kind of start is unbelievable," Espinosa said. "It's an unbelievable feeling. All the emotions are going through me. It's crazy."
Espinosa, called up from Triple-A on Wednesday, led off the third inning with a home run off Mike Pelfrey. Espinosa added an RBI single in the fifth, hit a grand slam off Ryota Igarashi in the sixth and doubled in the eighth.
"I got a couple of pitches up that I was able to drive. It went my way today. ... I couldn't have imagined this," Espinosa said.
After the slam, it took a friendly nudge from star Ivan Rodriguez to coax Espinosa out of the dugout for a curtain call from the 20,224 at Nationals Park. His parents and two younger sisters were in attendance.
"That was awesome -- the biggest rush. I could see my family up there and all the fans," Espinosa said.
Espinosa has three homers in his last four games. The performance earned him a whipped cream pie in the face -- instead of the traditional shaving cream variety, which might have damaged his contact lenses -- from teammate John Lannan.
Washington scored 13 unanswered runs to post its 60th win of the season, eclipsing the Nationals' total from both 2008 and 2009.
"It's one of those days where you really feel good about where your organization is going. ... We want to raise the bar a little higher than that, but it's a step," Washington manager Jim Riggleman said.
Rodriguez's two-run double ignited a five-run rally in the fourth. Michael Morse hit a tiebreaking single off Pelfrey (13-9) as the Nationals came back from a 3-0 deficit. Rodriguez finished with three RBI.
Scott Olsen (4-8) picked up the victory with four hitless innings of relief. It was Olsen's first appearance out of the bullpen since his 2005 rookie season. Collin Balester worked the ninth, finishing a three-hitter.
Despite breaking a six-game personal skid, Olsen said he felt uncomfortable pitching in relief.
"I don't want to be in the bullpen," he said. "I'd rather start, but that's not what they want me to do."
Pelfrey lost for the third time in five decisions. He allowed six runs on five hits and walked three.
"I just see a guy that kind of loses confidence and I see a guy that doesn't have the presence on the mound," Mets manager Jerry Manuel said of Pelfrey.
New York took a 2-0 lead in the first without benefit of a hit out of the infield. Angel Pagan dropped a bunt single, stole second, went to third when shortstop Espinosa bobbled Chris Carter's grounder and scored on David Wright's sacrifice fly. Jordan Zimmermann then walked the next three hitters, a free pass to Josh Thole forcing home a run.
Thole's RBI single made it 3-0 in the third.
After Espinosa's homer just inside the left-field foul pole in the third, the Nationals chased Pelfrey in the fourth. Washington batted around for the third straight game and Pelfrey walked three batters in the frame.
"They gave me a lead early and we got to the fourth inning and the wheels fell off," Pelfrey said. "I don't think you can walk three guys an inning ... and expect good things to happen."
Nyjer Morgan's RBI single finished Pelfrey. Raul Valdes relieved and hit Adam Kennedy with a pitch before walking Ryan Zimmerman with the bases loaded to force in a run.
Zimmermann worked four innings, allowing three runs -- one earned -- on three hits.
Rodriguez hit an RBI single in the sixth and Espinosa hit a grand slam off the right-field facade later in the inning.
Washington RF Willie Harris left the game for precautionary reasons with dizziness after crashing face-first into the scoreboard in right-center while trying to catch Carter's third-inning double. ... Nationals SS Ian Desmond (sore left hamstring) got the day off from the starting lineup, but struck out as a pinch-hitter in the eighth. ... Tuesday's game will feature two starting pitchers making their major-league debuts: Washington LHP Yunesky Maya and Mets RHP Dillon Gee. Maya is a Cuban defector who was 1-2 with a 3.38 ERA in five starts at three different minor-league levels, while Gee went 13-8 with a 4.96 ERA in 28 starts at Triple-A Buffalo. "This year has been unbelievable and especially to end it here. The main goal was just to go out this year and to prove that I'm healthy again," said Gee, who missed much of 2009 with a right shoulder injury. ... Riggleman said Rodriguez and rookie Wilson Ramos would split the starting catcher's job for the final month of the season. ... Pelfrey has a 10.98 ERA in two September starts after posting a 1.20 ERA in five August starts.