Mariners 5, Red Sox 3: Dustin Ackley singled in the tying and go-ahead runs in a five-run ninth as visiting Seattle battled back to stun Boston.

Koji Uehara (5-4) came on looking to polish off a shutout and sandwiched two outs around a single before a walk and another single loaded the bases. Austin Jackson ripped a two-run double off the wall in left and Ackley followed with a two-run single before scoring on Robinson Cano’s single to right to cap the five-run outburst.

Dominic Leone (6-2) earned the win in relief and Fernando Rodney worked a scoreless ninth to pick up his 37th save for the Mariners, who moved a half-game ahead of the Detroit Tigers for the second American League wild card. Felix Hernandez, who had not allowed more than two runs in an outing since May 12, surrendered more than that on one swing when Yoenis Cespedes sent a three-run blast over the “Green Monster” in the sixth to put the Red Sox on top.

Hernandez was charged with three runs on five hits and two walks while striking out seven in 5 2/3 innings. David Ortiz and Daniel Nava each doubled and scored for the Red Sox, who have dropped six straight, while Joe Kelly allowed one hit in five innings but was denied his first win with Boston when Uehara broke down.

Nava led off the sixth with a double and moved to third on a groundout before Ortiz was intentionally walked. Cespedes fouled off three straight pitches before blasting a 2-2 changeup out of the stadium for his 21st home run.

GAME NOTEBOOK: The Red Sox reportedly signed Cuban OF Rusney Castillo to a seven-year, $72.5 million deal. … Boston 1B Mike Napoli (back spasms) missed his third straight game. … Hernandez, who has failed to complete six innings in two straight turns after going at least seven in his previous 16 starts, hit Red Sox SS Xander Bogaerts in the head with a pitch in the fifth. Bogaerts stayed in the game and took the field the next half-inning but was replaced by a pinch hitter in his next at-bat and will be evaluated for a concussion.