NEW YORK -- The term "next man up" is most often associated with the NFL. But the injury-plagued New York Mets are winning with the mantra as they pursue a National League wild-card berth.

The next "next man up" is left-hander Sean Gilmartin, who tries to nudge New York closer to the playoffs when he makes his first start of the season Saturday night in the third contest of a four-game series against the Philadelphia Phillies at Citi Field.

The Mets won the first two games of the series including Friday, when they used six pitchers to piece together a 10-5 victory.

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New York (82-72) moved one game ahead of the San Francisco Giants (81-73) in the race for the NL's first wild card by virtue of Giants' 7-2 loss to the San Diego Padres late Friday night.

The St. Louis Cardinals, who lost 5-0 to the Chicago Cubs earlier Friday, are a half-game behind the Giants.

Gilmartin is taking the rotation spot usually occupied by ace right-hander Noah Syndergaard, who was supposed to start Saturday but was pushed back at least a couple days because of a bout with strep throat.

Gilmartin made 18 starts this season at Triple-A Las Vegas, but has not pitched more than two innings or thrown as many as 20 pitches since he was recalled by the Mets on Aug. 25.

"Got to turn to Sean Gilmartin (and) say 'Hey look, you've got to step up, here's your chance,'" Mets manager Terry Collins said.

Syndergaard's illness is the latest roadblock encountered by the Mets, who expected right-hander Jacob deGrom (right elbow) and left-hander Steven Matz (left shoulder) to return to the rotation this week but instead learned they are done for the season.

The Mets have three rookies in their rotation -- Robert Gsellman, Seth Lugo and Gabriel Ynoa, the latter of whom started Friday in place of Matz and allowed two runs in two innings.

"You're numb to it now, it's happened so much," Collins said of the constant upheaval.

The Phillies, meanwhile, send rookie right-hander Alec Asher to the mound as Philadelphia (69-85) looks for the consistency it lacked the previous two nights. The Mets came back from ninth- and 11th-inning deficits to win Thursday's series opener 9-8 and trailed 3-1 after four innings Friday.

"The next step is for all these guys to get better," Phillies manager Pete Mackanin said. "That's how you win. You've got to have consistency."

Gilmartin is 1-1 with a 1.93 ERA in 10 career appearances against the Phillies, who were the opponent for his lone previous career start last Oct. 1. He took the loss after giving up two runs over five innings in Philadelphia's 3-2 victory.

Asher gave up five runs over a career-low two-thirds of an inning in his lone previous start against the Mets last Sept. 30.