Washington will send veteran right-hander Max Scherzer (9-5, 2.60 ERA) against Atlanta rookie right-hander Mike Soroka (11-3, 2.53). They rank second and third among the ERA leaders in the National League.
The Braves have won the first three games in the series. Their 5-4 victory on Saturday night was their season-best ninth straight victory and set a franchise record with a 13th consecutive home win.
Atlanta improved its lead in the National League East to 10 games over the Nationals and lowered their magic number to 11.
"We're still a confident group here," Washington's Patrick Corbin said. "We're still in a good position to do stuff, so we still have the confidence to do something."
The starting matchup for Sunday has all the luster of a playoff game.
Soroka will be making his third start of the season against the Nationals. He is 0-1 with a 3.00 ERA over 15 combined innings. He last faced the Nationals on July 31 and received a no-decision despite giving up only one hit in seven innings.
Soroka wasn't dominant his last time on the mound against the Toronto Blue Jays on Sept. 2. He got the win after allowing three runs, five hits, two walks and six strikeouts in five innings.
Scherzer has been working through some injury issues, spending one stint on the injured list with a mid-back strain and another with a mild rhomboid strain.
In his last start against the New York Mets on Sept. 3, Scherzer also took a no-decision after allowing four hits over six innings. Over his last three starts, Scherzer is 0-0 with a 4.40 ERA and has twice failed to pitch past the fifth inning as the club is being cautious with him with an eye on the postseason.
"It was definitely a step forward," Scherzer said. "I felt like I was able to start bringing some intensity to the pitches, especially getting six innings. There was a lot of good in this start."
Scherzer will be making his 21st career start against the Braves. He is 9-7 with a 3.76 ERA in 22 previous appearances. This will be his first start against Atlanta this season.
Markakis, out since July 26 with a fractured left wrist, is expected to participate in simulated games next week when the team visits the Philadelphia Phillies. Inciarte, out since Aug. 16 with a strained right hamstring, has been taking swings in the cage and has been running with 60 percent effort.
"Nick is doing well," said Atlanta manager Brian Snitker. "He's taking batting practice and doing everything. Hopefully we'll get him in some sim games in Philadelphia and see where we are."
The Nationals may be without catcher Kurt Suzuki. He left Saturday's game for a pinch-hitter in the eighth inning after being struck by a foul ball in the previous inning.
--Field Level Media