The game was tied at 1 when New York took the lead in the bottom of the sixth inning. After Luis Castillo led off with a double and Carlos Beltran walked, Sheffield came to the plate, swung at the first pitch and hit a three-run homer over the left-field wall.
Manager Manny Acta didn't believe the ball was over the wall. He argued with third-base umpire Adrian Johnson that a fan had reached over the railing and touched it, and that the hit should have been ruled an RBI double with runners on second and third.
The umpires huddled before deciding to look at the video replay. It marked the second time in two years that the Nationals were involved in the practice. The first came on Sept. 27, 2008, against the Phillies, with the umpires upholding a home run hit by Washington outfielder Kory Casto.
This time the umpires took six minutes to determine that Sheffield had, indeed, hit a home run.
Through an umpire's attendant, crew chief Larry Vanover declined to comment about the ruling, but Acta felt the hit should have been ruled a double.
"From the dugout, I didn't think the ball was out," Acta said. "We have all those rules with the replay, and we have to abide by them. If you have to reach over the railing, which is right on top of the wall, I don't think the ball would have gone out of the ballpark. But I've been wrong plenty of times before."
Third baseman Ryan Zimmerman, who had a good view of where the ball landed, was the one who signaled Acta to protest the call. After the game, Zimmerman didn't complain about the final ruling.
"It looked like [the fan] reached over," said Zimmerman. "I don't know. They went and looked at the replay -- it is what it is."
Lannan exited but was charged with another run in the inning. With Jesus Colome on the mound, Ramon Martinez hit a sacrifice fly to bring home David Wright.
Lannan ended up pitching five-plus innings and gave up five runs. He walked four batters, and three of them scored.
"I felt OK, but I struggled with two strikes," Lannan said. "I knew I had to get the three, four and five hitters in the sixth. I was ready for it. It just didn't go my way. It always stings when you walk guys. I shouldn't have walked those guys. It does stink. I have to be more aggressive with two strikes."
The Nationals made the game interesting in the top of the seventh. Mets reliever Bobby Parnell entered the game and had a tough time throwing strikes. With the bases loaded, he walked Zimmerman to force home Wil Nieves.
Left-hander Pedro Feliciano entered the game to face the left-handed-hitting Adam Dunn, who hit a fly ball to right fielder Angel Pagan for the second out of the inning. Right-hander J.J. Putz came in to face Austin Kearns, who grounded out to end the inning on a 3-2 pitch.
The Nationals ended up leaving 13 runners on base.
"Later in the game, we had a couple of opportunities with runners on third with less than two outs, and we couldn't do anything either," Acta said.
Right-hander John Maine started for New York, lasting six innings and giving up one run.
Washington took the lead in the top of the second inning, when Nieves singled to right field to drive in Willie Harris, but New York would tie the score an inning later, when Pagan scored on a single by Sheffield.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.