Andrelton Simmons’ two-run homer off Ross Detwiler capped Atlanta’s four-run seventh inning which erased the Nationals’ 4-0 lead.
Morse had a quick answer by hitting right-hander Chad Durbin’s first pitch over the wall in right field leading off the eighth.
The Nationals, who swept a three-game series in Atlanta on May 25-27, are 5-1 against the Braves this season. NL East-leading Washington is 4½ games ahead of Atlanta. The Nationals began the night 3½ games ahead of the Mets.
Jesus Flores homered and Ian Desmond had a two-run single for Washington.
Sean Burnett (1-1) gave up one hit in 1⅓ scoreless innings. Tyler Clippard gave up a leadoff double to Freddie Freeman in the ninth before recovering for his 13th save.
Clippard walked Martin Prado with one out, putting runners on first and second. Michael Bourn flied out to center and Clippard ended the game on Simmons’ flyball to right.
Durbin (3-1) gave up two hits and a run while recording two outs in the eighth. Jonny Venters struck out Bryce Harper with the bases loaded to end the inning.
Detwiler allowed only two hits through six scoreless innings, but he couldn’t hold the 4-0 lead in the seventh.
Detwiler hit Freeman with a pitch and then bobbled a bunt by Jack Wilson, who was awarded an infield hit. A balk by Detwiler moved the runners to second and third.
Pinch-hitter Prado’s single drove in Freeman. Bourn’s fly ball scored Wilson, and Simmons followed with his tying two-run homer, knocking Detwiler out of the game.
Detwiler gave up four runs, five hits and a walk in 6⅔ innings.
Randall Delgado lasted only four innings, giving up seven hits and four runs, two earned.
Delgado was hurt by third-inning errors by second baseman Jack Wilson and Simmons, the rookie shortstop, which led to two unearned runs.
Wilson, starting at second base for the first time this season, dropped a grounder by Adam LaRoche for the first error with two outs. Morse singled past Chipper Jones at third. Simmons retrieved the ball in shallow left and threw past Wilson at second base for another error, allowing the runners to advance. Desmond drove in LaRoche and Morse with a single to left.
Detwiler was 0-for-14 this season before his second-inning single drove in Morse, who had singled, for Washington’s first run. Flores pushed the lead to 4-0 with his homer off Delgado in the fourth.