BOSTON -- On the day Seattle manager Lloyd McClendon said his contending Mariners were officially starting their stretch run, the Boston Red Sox tried to play spoilers.
Well, if that's the case, his team, seeking the franchise's first postseason berth since 2001, started its stretch run toward the playoffs with a dramatic win.
Down 3-0 and facing Boston closer Koji Uehara (5-4), the Mariners rallied for five runs, doing most of their damage with two outs, and sent the last-place Red Sox to their sixth straight loss -- a stunning 5-3 defeat that took Seattle ace Felix Hernandez off the hook.
Seattle came into the game a half-game behind the Detroit Tigers for the second wild-card spot in the American League.
After Seattle right fielder Endy Chavez worked an 11-pitch walk to keep the game alive, pinch-hitter Chris Denorfia singled to load the bases. Center fielder Austin Jackson doubled home two runs and left fielder Dustin Ackley dropped a two-run single into short left. Second baseman Robinson Cano then singled on a 3-2 pitch and Ackley, taking advantage of a lazy throw by right fielder Daniel Nava, scored all the way from first.
The Red Sox came into the game 44-0 when leading after eight innings.
Rookie right-hander Dominic Leone (6-2) got the win and right-hander Fernando Rodney pitched the bottom of the ninth for his 37th save.
Boston left fielder Yoenis Cespedes hit a three-run homer off King Felix in the sixth inning and the shot looked like it would stand up.
Cespedes, who left Wednesday night's game because of a medical emergency reportedly involving his mother, barely stayed alive with a two-strike foul tip before he hit a 2-2 pitch completely out of Fenway Park for his 21st homer of the season -- his fourth for the Red Sox.
Hernandez failed to win for the seventh straight time on the road (he's just 0-2).
Right-hander Joe Kelly pitched the first five innings for the Red Sox, allowing one hit and leaving with what appeared to be a back injury. Left-hander Craig Breslow, right-hander Burke Badenhop and lefty Tommy Layne got the game to Uehara, who blew his third save in 29 chances.
Kelly is 0-1 with three no-decisions with the Red Sox.
Red Sox rookie shortstop Xander Bogaerts was hit on the helmet by an 89 mph Hernandez pitch in the fifth inning and left an inning later. He was being evaluated for a concussion.
Boston designated hitter David Ortiz had two hits and two walks in four plate appearances, reaching base four times for a fourth straight game. He is 16-for-28 on the current homestand.
The Red Sox fell to a season-worst 16 games below .500.
Boston had first and third with one out in the first inning against Hernandez. Cespedes then hit into a 5-4-3 double play.
Hernandez struck out the first two batters in the second inning when slumping shortstop Xander Bogearts, 1-for-22 on the homestand coming in, hit a towering drive down the left field line. Third base umpire Pat Hoberg waited until he was sure and called it foul. Boston manager John Farrell came out and umpire crew chief Larry Vanover called for a review. The call was not reversed because the replays were inconclusive.
Bogaerts then struck out. It was Hernandez's 200th strikeout of the season, his club-record sixth straight 200-K campaign. Randy Johnson holds the club record of seven 200-strikeout seasons but didn't have six straight.
The same umpire was involved in a fourth-inning review.
With a runner on first and two out, Seattle DH Kendrys Morales hit a sinking liner to left-center field. Center fielder Mookie Betts caught the ball, but it bounced inside his glove and Hoberg called it no catch. Betts, trotting off the field, realized Ackley was running -- and Betts threw the ball home, where no one was covering. Out came Farrell and this call was flipped, keeping the game tied.
Ortiz lined his second hit, a double, with one out in the fourth but Hernandez notched his fifth and sixth strikeouts to escape.
Kelly worked around a hit batter, two walks, an error and a visit from Farrell and the trainer during the fifth, his back apparently stiff. But he retired Jackson with the bases loaded to end that threat. That was the end of his night.
Hernandez hit Bogaerts in the helmet with one out in the fifth. Bogaerts stayed in the game and Hernandez stranded him at first.
NOTES: The Red Sox reportedly reached an agreement with OF Rusney Castillo, a 27-year-old Cuban defector who would receive a seven-year, $72.5 million contract that actually begins this season. No announcement was made Friday, with manager John Farrell saying, "I'm aware of the reports. There's still some administrative things that he would have to go through until anything is announced officially, so until that time, I'm kind of like everybody else -- I've read the reports." Castillo would likely become a center fielder in Boston and could be in the lineup soon. ... Seattle RHP Chris Young looks for his career-high 13th win when he faces RHP Brandon Workman in Game 2 of the series Saturday. Workman has lost in seven straight appearances, six of them starts.