WASHINGTON -- For the second time in three seasons, the Washington Nationals will head to the postseason with the top seeding in the NL.
They hope they can take advantage of that this year.
The NL East champion Nationals locked up home-field advantage until the World Series by beating the Miami Marlins 4-0 on Doug Fister's three-hitter in the opener of a day-night doubleheader Friday.
Washington improved to 94-65, meaning it can finish no worse than tied with the Los Angeles Dodgers for the National League's top record. But the Nationals own the tiebreaker because they won the teams' season series 4-2.
"It's important to have home-field advantage. If we want to get to where we want to get to, then that's important. So that's accomplished," rookie manager Matt Williams said. "I also think it's really important for us to play really well the next three games and continue to push and play with some enthusiasm and determination, because that light switch just doesn't turn on and off."
Washington improved to 49-29 at Nationals Park, giving the team a chance to finish the regular season tied with the AL's Los Angeles Angels for the best home record in the majors.
"That was a big milestone for us today. I think that's going to give us some edge in the playoffs," said Fister (16-6), who threw the second shutout of his career, had nine strikeouts and zero walks, and hit one batter. "It's always nice to be home. You've got your home fans, we've got our own lockers, our own chairs, whatever it may be. Guys are comfortable here. And that means a lot."
Then again, Washington knows full well being the highest-seeded club guarantees nothing. The Nationals led the majors with 98 wins in 2012, but were eliminated in the NL division series by wild-card St. Louis.
This year, they clinched their division title Sept. 16, and have gone 7-2 since then, pushing for the NL's top record.
The only player who got a hit off Fister was Donovan Solano, with a pair of harmless singles in the first and fourth innings, and a triple with two outs in the ninth. The next batter, Casey McGehee, lined out to diving second baseman Asdrubal Cabrera.
Fister threw 104 pitches, 77 for strikes, and heard a loud ovation when he jogged from the dugout to the mound for the ninth.
"Obviously some adrenaline, some emotions run through there," the lanky righty said. "It's one of those things where you kind of take a second and you soak it in and then you get back to work."
Fister produced at the plate. He doubled then scored on Ryan Zimmerman's single in the sixth, and later drew a walk.
Washington's Anthony Rendon hit a solo shot to left off wild-as-can-be Jarred Cosart (4-4 with the Marlins; 13-11 overall in 2014, including his time with the Astros) with one out in the first, his 21st homer of the season.
Adam LaRoche scored later in the first on a passed ball, and Cabrera added an RBI infield single in the fifth after two of Cosart's career-high eight walks.
"They have everything they need over there to win a World Series," Cosart said.
Only two regular members of Washington's lineup, right fielder Jayson Werth and catcher Wilson Ramos, were in Williams' batting order for Friday's second game; both sat out the opener. Washington's pitcher, Taylor Hill, was going to make his first major league start.
At 76-83, the Marlins could finish anywhere from second to fourth in the NL East, but they know they won't finish last.
Nationals: CF Denard Span returned to action for the first time since leaving Tuesday's game after a diving, tumbling catch that left his right knee scraped and sore. Span started in center and hit in his usual leadoff spot, going 1 for 4 with a walk. Afterward, he said he felt rusty but fine. ... Zimmerman started in left field for the second day in a row as he works his way back from a hamstring injury that sidelined him for 55 games.
Williams said the Nationals will stick to their planned starting pitchers this weekend, including RHP Stephen Strasburg (13-11, 3.23 ERA) for a last pre-playoffs tuneup Saturday against Marlins RHP Nathan Eovaldo (6-13, 4.44).