Mariners 5, Nationals 3: Dustin Ackley homered and had four RBIs as host Seattle salvaged the finale of the three-game series against Washington.

Ackley hit the decisive three-run homer in the fifth inning as the Mariners moved within a half-game of the Detroit Tigers for the American League’s second wild card. Bryce Harper hit two homers for the Nationals, who saw their lead in the National League East decrease to six games over the Atlanta Braves.

Hisashi Iwakuma (13-6) allowed three runs and five hits in six innings and didn’t issue a walk for the 13th time in 23 starts. Fernando Rodney worked around a single to Harper to start the ninth to retire the side and record his 39th save to halt Seattle’s three-game losing streak.

The Mariners trailed 3-1 when Brad Miller and Austin Jackson hit consecutive one-out singles off Tanner Roark (12-9) in the fifth. Ackley followed by smashing a three-run blast to right field to push Seattle ahead and Endy Chavez added insurance with a run-scoring double in the eighth.

Harper hit his first homer with one out in the second inning and Nate Schierholtz led off the third with a shot over the center-field fence to make it 2-0. Ackley delivered a run-scoring single in the third to get the Mariners on the board before Harper went deep for the second time with one out in the fourth.

GAME NOTEBOOK: Roark allowed four runs and 11 hits in 6 1/3 innings. … Jackson went 3-for-4 to extend his hitting streak to 11 games. … Washington hit 10 homers during the series – led by a season-high six in Friday’s victory.