WASHINGTON — On a brisk, damp night that hinted of October, Washington Nationals starter Gio Gonzalez pitched like a man determined to make an impact in the playoffs.
Gonzalez (10-10) struck out a career-high 12 batters and allowed just one hit through seven innings as the Nationals defeated the New York Mets 3-0 in the late game of a day-night doubleheader to salvage a split.
It's not yet certain whether he or Tanner Roark will be the fourth starter in the rotation when the NL East champion Nationals begin postseason play on Oct. 3.
"I missed a month and I just want to come back and try to do my best and contribute," said Gonzalez, who missed a stretch of May and June with shoulder inflammation. "To do my best to stay a part of this magic that we've got going."
In Thursday's first game, Ryan Zimmerman's healing hamstring appeared to pass a seven-inning test for playoff-bound Washington in a 7-4 loss.
The split pulls the Nationals within one win — or one Los Angeles Dodgers loss — of clinching the National League's top record and home-field advantage until the World Series.
In the second game, Zack Wheeler (11-11) allowed three runs over five innings as the Mets (77-82) were ensured of their sixth consecutive sub-.500 season.
The Nationals did their damage off Wheeler in the fourth on a fielder's choice, a passed ball, and one of three singles by Anthony Rendon.
"They hit one ball hard the whole night," said Wheeler, who allowed four hits and three walks. "It was just one of those games where they were finding holes and they were dropping in. It's not the way I wanted to go out this year."
Drew Storen worked a perfect ninth for his 11th save, closing out the first of two day-night doubleheaders in as many days for Washington.
Gonzalez kept his strong September going. He struck out the side in the second and third innings and faced the minimum number of batters through five innings before issuing solo walks in the sixth and seventh.
"I mean, I've had some fun outings this year," Gonzalez said, "but (I was) definitely more aggressive this time in the strike zone. And, that's a lot of credit to the catcher Willy (Ramos). . We just wanted to attack these guys."
He fanned Lucas Duda for a third time in the seventh for his career-best 12th strikeout, passing the mark he'd tied five times, including three times last season. After Wilmer Flores lined out to end the inning, Gonzalez walked to the dugout to chants of "Gi-o! Gi-o!" from the Nationals Park crowd.
Manager Matt Williams hasn't officially announced the club's playoff rotation. Despite Roark's breakout year, it's expected Gonzalez, Washington's only southpaw starter, will join Stephen Strasburg, Jordan Zimmermann and Doug Fister.
Gonzalez has battled inconsistency, but posted a 2.48 ERA in September (compared to a 3.57 ERA for the season), as well as seven consecutive quality starts.
In the early game, Washington's Zimmerman continued his quest to get healthy by hitting, running the bases and playing left field for seven innings to Williams' satisfaction.
"It was less thinking about it, I think, which is exactly what we want," said Williams, who added that the two-time Silver Slugger winner could've finished the game if needed. "We want him to be able to react out there. I thought it was fine today."
Matt den Dekker singled home the go-ahead run off Tyler Clippard (7-4) in the eighth inning. Flores drove in den Dekker from second with an infield single to add an insurance run, and Ruben Tejada singled home another run in the ninth.
Curtis Granderson had three singles and three RBIs as New York belted 15 hits. Flores also had three singles.
"I'm just getting hits," said Granderson, who has struggled since joining the Mets this year, but now has eight multi-hit games in September. "I really wish it was more complicated than that, but sometimes you find a little bit of grass or a couple of holes here or there. That's really it."
Zimmerman went 1 for 4 and played left field in his second start since straining the hamstring in late July. He also lined out in a pinch-hit appearance in the nightcap.
Zimmerman scored in the fourth after singling, going first-to-third at less than full pace on Adam LaRoche's single, and running home at a similar speed on Ian Desmond's sacrifice fly to center.
"I can't really go 100 percent yet," said Zimmerman, who played seven innings Saturday but has had soreness as weather reduce him to one pinch-hit appearance since. "I'm sort of learning what I have, what I don't have, and the only way to do that is to go out and play."
Carlos Torres (8-5) pitched the seventh, and Jenrry Mejia worked the ninth for his 28th save.
With Zimmermann (13-5, 2.78) starting Sunday, the right-hander could start the first or second game of next week's NLDS on four or five days' rest, as long as he shows no ill effects from a line drive taken to his throwing shoulder last Saturday.
Nationals: CF Denard Span (right knee soreness) was left out of Thursday's games two days after he departed following a tumbling catch in the series opener. Williams said he expects him to play Friday.
Mets: After 3B David Wright (inflamed left shoulder) said Wednesday he's in the beginning stages of a six-week rehab program in hopes of avoiding surgery, manager Terry Collins Thursday said he may be more aggressive in resting Wright next season. "What I've got to do is forget about the asking and just give him some time off," Collins said. ... C Travis d'Arnaud (unspecified ailment) will not play at least until he sees Mets team doctors Friday, Collins said.
Nationals: RHP Doug Fister (15-6, 2.55) will make the early start Friday against Miami RHP Jared Cosart (13-10, 3.70), and RHP Taylor Hill (0-0, 4.15) will make his first major league start against LHP Andrew Heaney (0-3, 5.33) late.
Mets: LHP Jonathan Niese (9-11, 3.50) will attempt to reach the 10-win plateau for the third time in his career in a series opener against Houston's Brad Peacock (4-9, 4.82).