A season-ending three-game series between the New York Mets and Washington Nationals was supposed to have the NL East title at stake.

Instead, the Mets are vying for home-field advantage in next week's NL division series while the Nationals play out the string in what has been a disappointing season.

The division-winning Mets look to extend their longest winning streak over the Washington franchise in 24 years Saturday in a day-night doubleheader.

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New York (89-70) and Washington (81-78) switched spots as the division leader eight times this year. The Mets, however, moved ahead for good following a 12-1 win at Miami on Aug. 3, a day after pulling level by completing a three-game sweep of Washington.

They swept the Nationals again from Sept. 7-9, taking control of the East with a seven-game lead before clinching it last weekend.

The only remaining race left for New York involves home-field advantage in the NLDS, which starts next Friday against Los Angeles.

New York fell 3-0 at Philadelphia on Thursday to get swept in the three-game set, and their chance to bounce back was moved back a day after rain caused Friday's postponement.

"It's easy to say, 'Let's just gear up for the playoffs,'" third baseman David Wright told MLB's official website. "But home-field advantage would be nice, so I think that's something that we really need to bear down these last three games and try to attain. And it would be nice to go into the playoffs with some sort of momentum."

Facing the Nationals, losers of seven of their last 10, should be just what the Mets are looking for. They're aiming for their first seven-game winning streak against Washington since taking nine straight when the franchise was the Montreal Expos in 1991.

Noah Syndergaard (9-7, 3.34 ERA) takes the ball, and he's 1-0 with a 2.08 ERA and 13 strikeouts in 13 innings over two starts against the Nationals.

The rookie right-hander was outstanding last Friday, striking out 11 and allowing two runs in 7 2-3 innings of a 12-5 win at Cincinnati. He helped himself with a pair of hits, including an RBI single.

That was enough for manager Terry Collins to declare Syndergaard will be in the postseason rotation.

"He's going to start the game, whatever game it may be. I'm very impressed," Collins said. "This kid's really gotten better."

Syndergaard will try to be better at Citi Field, where he's 0-1 while surrendering nine runs and three homers in 12 2-3 innings of his last two starts after going 7-1 with a 1.82 ERA through his first nine.

Yoenis Cespedes was included in the lineup Friday, so his fingers aren't an issue after being hit by a pitch in Wednesday's 7-5 loss at Philadelphia.

He's 7 for 18 with two homers, three doubles and seven RBIs in his last four meetings with Washington.

Matt Harvey (13-7, 2.80) will also be in the Mets' postseason rotation, and he takes the ball in the nightcap. He's 1-0 while allowing two runs with 13 strikeouts and one walk in 11 2-3 innings over his last two starts. The right-hander went 6 2-3 while yielding two runs in last Saturday's 10-2 win at Cincinnati that clinched the Mets' first division crown in nine years.

Harvey is 3-2 with a 1.95 ERA in nine career starts against Washington, going 2-1 with a 1.07 ERA in five at home.

The Nationals won 3-0 on Thursday to salvage a victory from a three-game set at Atlanta.

''Everybody in here is disappointed how the season turned out, but at the same time, it would be huge to go into New York and play our best baseball,'' Thursday's starter Stephen Strasburg said. ''Hopefully we can get them into a little slump heading into the playoffs. That's all we can do.''

Max Scherzer (13-12, 2.91) gets the nod opposite Harvey to conclude his first season with Washington. The right-hander is 2-1 with a 2.12 ERA and 34 strikeouts in 29 2-3 innings over his last four starts. That came after he was roughed up for five runs and three homers in six innings in an 8-5 loss to the Mets on Sept. 7.

Scherzer yielded four runs - one earned - over 14 2-3 innings while striking out 18 in his first two starts against New York.

He came within five outs of his second no-hitter of the year Monday, allowing one run and two hits with 10 strikeouts in eight innings of a 5-1 win over Cincinnati.

"The obvious thing for me," Reds manager Bryan Price said, "is that he got stronger as the game went on."

The Nationals turn to Gio Gonzalez (11-8, 3.93) in the opener and he's looking for another sterling effort against the Mets. The left-hander is 6-1 with a 1.68 ERA and 9.23 strikeouts per nine innings over 10 starts in Queens.

He's 3-0 with a 1.09 ERA and 31 strikeouts in 24 2-3 innings during his last four overall matchups with New York.

Gonzalez allowed two runs in five-plus innings while not getting a decision in Sunday's 12-5 loss to the Phillies. The effort was overshadowed by a dugout fight between Jonathan Papelbon and Bryce Harper, highlighted by the closer choking the superstar right fielder.

Papelbon has been suspended for the rest of the season.