NEW YORK -- The Washington Nationals exited the final series of the first half with a healthy division lead and a sense things could get even better in the coming weeks. The New York Mets were left to rely on the hope that history will repeat itself.

Daniel Murphy remained a thorn in the side of his former club Sunday, when his two-run homer in the first inning gave the Nationals a lead they'd never relinquish in a 3-2 win over the New York Mets.

The Nationals (54-36) won the final three contests of the four-game series to extend their National League East lead over the Mets (47-41) to six games. Washington has been alone atop the NL East for the last 43 days and has held at least a share of the lead every day since May 12.

"It was a good first half, feel good about it," Nationals left fielder Jayson Werth said. "I think we still haven't played our best baseball."

The Nationals' run-differential of plus-105 is second-best in baseball behind only the Chicago Cubs (plus-139) Washington has the best run-differential in the NL since June 1 (plus-49).

In addition, Murphy leads the majors with a .348 batting average while his fellow All-Stars Stephen Strasburg and Max Scherzer are the only teammates in baseball with 10 wins at the break. Strasburg is the first NL pitcher to go 12-0 before the All-Star Break in more than 100 years while Scherzer is 5-2 with a 1.66 ERA in his last eight starts.

"We're really starting to mesh," Werth said as he linked his hands together. "You can kind of feel it. You've got that good feeling going into the break (that) you can come back and you can really do some things in the second half. Hopefully, that'll be us in the second half."

The Mets, who could have tied the Nationals atop the NL East with a sweep, are taking solace in what they achieved last season, when New York trailed by as many as 4 1/2 games on July 5 before surging past Washington in August and winning the division by six games on its way to the World Series.

"We're still in the race," Mets manager Terry Collins said. "We've been in this situation one year ago, where things looked bleak. We end up playing in the World Series. So we're going to take the rest and get ready for the second half."

The best news for the Mets heading into the break might be that they won't have to see Murphy for six more weeks. Murphy, who won NL Championship Series MVP honors for New York last fall before signing with the Nationals in December, went 1-for-4 Sunday to "drop" his average against the Mets this season to .423 (22-for-52).

He was 7-for-17 with three homers and 10 RBIs in the series and has seven homers and 21 RBIs in 13 games overall against the Mets.

"He is definitely a cyborg right now," said Nationals left-hander Gio Gonzalez, who earned the win after allowing two runs on four hits and four walks while striking out three over 5 2/3 innings. "You don't even know what to throw him anymore. You might have to go there and throw a ping-pong ball, sneak it by him. But I doubt it."

Wilson Ramos, who will also represent the Nationals at the All-Star Game, had what proved to be a decisive RBI single in the third. Right-hander Tanner Roark, a usual member of the Washington rotation, threw 2 1/3 perfect innings before Jonathan Papelbon earned his 19th save with a one-hit ninth.

"You want to win this last game, you want to feel good about yourselves over the break," Nationals manager Dusty Baker said. "You hope the guys take some time off but (will) kind of be itching come Thursday to get back to work."

Jose Reyes, who rejoined his original major league team Tuesday, hit two homers for the Mets. It was the first two-homer game for Reyes since Sept 27, 2011 -- the penultimate game of his first stint in New York.

Left-hander Steven Matz (7-5) remained winless in his last eight starts after allowing three runs on six hits and four walks while striking out five for the Mets, who finished 7-4 on a season-long 11-game homestand.

"We didn't flip any switches last year -- we just ground out game after game," Collins said. "And we've got to do that."

NOTES: Mets OF Yoenis Cespedes (strained right quad) missed his second straight game. Cespedes said he wasn't sure if he'll be able to return when the second half resumes on Friday. ... The 11-game homestand was the Mets' longest since an 11-game stretch in September 2013. LHP Steven Matz is the first Mets' pitcher to start three games in a homestand since RHP Bobby Parnell accomplished the feat in 2009. ... The save for RHP Jonathan Papelbon was the 377th of his career breaking a tie with Jeff Reardon for ninth place on the all-time list. ... The Nationals reached the All-Star Break with at least a share of first place for the third straight season and the fifth time since moving to Washington in 2005. It also accounted for the 10th time in the franchise history of the Nationals/Montreal Expos.