Rookie southpaw Tommy Milone can continue Washington's game series with Florida at Sun Life Stadium, the Marlins' last before moving into a new ballpark for 2012.
The Nationals enter the series at 78-80 overall with three games to play.
They climbed within two games of the break-even point on Sunday in Washington, when Michael Morse and Wilson Ramos each hit a two-out home run as the Nationals blanked the slumping Atlanta Braves, 3-0, in the rubber match of a three-game series.
Ross Detwiler (4-5) scattered four hits and walked two over six innings for Washington, which finished the season with a 44-36 record at home. Henry Rodriguez, Tyler Clippard and Drew Storen each tossed a perfect inning to preserve the shutout.
Milone, a 24-year-old, made his big-league debut on Sept. 3 and is unbeaten in four starts in September.
The 24-year-old got no-decisions against the New York Mets and Houston in his initial two outings, then beat the Mets on Sept. 15 in New York for win No. 1 after allowing a run on three hits in 5 2/3 innings.
He followed up with six innings of shutout ball en route to a no-decision in the Nationals' 4-3 win at Philadelphia on Sept. 20.
Milone has given up 21 hits and eight runs in 21 2/3 innings across four starts in which the Nationals are 4-0.
The Marlins, who'll move to a new baseball-only stadium next season, begin the farewell series with right-hander Anibal Sanchez, who's never lost to the Nationals.
The 27-year-old Venezuelan is 7-0 in 16 career starts against Washington, posting a stingy 1.99 earned run average in 99 2/3 innings while walking 41 batters and striking out 82.
He last faced the Nationals in consecutive starts on May 8 and 14 and got a win and a no-decision while allowing five hits in 15 shutout innings with two walks and 20 strikeouts.
Sanchez is 1-2 in four September starts, including a 4-0 loss to Atlanta in his most recent outing in Sept. 20.
On Sunday in Milwaukee, George Kottaras led a balanced attack with two runs batted in, as the NL Central champion Brewers beat the Marlins, 9-5, to sweep the season series.
Ricky Nolasco (10-12) got blasted to the tune of seven runs -- six earned -- on nine hits over two-plus innings.
The Marlins have won 10 of 15 over the Nationals this year, with the two clubs splitting six meetings so far in Florida.