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04/02/12 5:02 PM ET

Espinosa goes deep in Nats' loss to Red Sox

FORT MYERS, Fla. -- With a roster decision or two still looming for both clubs as the Grapefruit League season ends, the Red Sox used a three-run fourth inning to beat the Nationals, 4-2, at JetBlue Park on Monday afternoon.

Boston right-hander Aaron Cook's only blemish in five innings of two-hit ball was a solo home run from Washington's Danny Espinosa in the top of the fourth. Nats right-hander Jordan Zimmermann gave up three runs (two earned) in his five innings, allowing six hits and one walk while striking out two.

The Red Sox finished their inaugural season at their new Spring Training complex 15-11-4, while the Nationals ended at 12-16-3.

Espinonsa's homer to center on a 1-0 pitch from Cook opened the scoring. Boston's rally in the bottom of the inning started with the middle of the order, on an Adrian Gonzalez single and David Ortiz double. A Kevin Youkilis groundout plated Gonzalez, and Darnell McDonald singled to make it 2-1. A sacrifice fly from Mike Aviles brought home another run.

Zimmermann, who tossed 57 of his 77 pitches for strikes, was not as sharp as his last outing, when he tossed six shutout frames against the Mets, but he was nonetheless effective and leaves Florida with a 3.38 ERA in six outings.

"I thought it went pretty well," Zimmermann said. "I never really built up before. I usually came in the spring ready to go 100 percent, and this year I tried building my way up a little bit. [I] came in about 75 percent ready to go. I did the build up thing, and it worked pretty well for me, so I'm happy with everything."

Cook threw 70 pitches, 43 for strikes, walked one and struck out two. In four Grapefruit League appearances, the right-hander posted a 1.88 ERA over 14 1/3 innings. Cook, who signed a Minor League deal in the offseason, will likely start for Triple-A Pawtucket, and he can opt out of his contract if he's not on Boston's 25-man roster by May 1.

"The plan is to go to Pawtucket and make a few starts and just try to stay ready, keep building my pitch count up, getting deep into games and see what happens," said Cook.

The right-hander said he "had a great spring."

"I've been able to mesh with the guys on the team," said Cook. "The organization is awesome. I wouldn't have it any other way."

Vicente Padilla, who is trying to make the Sox's Major League roster as a reliever, threw a perfect sixth inning.

Up next: The Red Sox and Nationals will meet for a second straight day on Tuesday, this time away from Florida and the Grapefruit League and at the Nats' summer home, Nationals Park. Clay Buchholz is scheduled to pitch for Boston, while Washington will counter with Edwin Jackson in a 3:05 p.m. ET contest airing live on MLB.TV.

Evan Drellich is a reporter for MLB.com. Follow him on Twitter @EvanDrellich. This story was not subject to the approval of Major League Baseball or its clubs.