ARLINGTON, Texas -- It was billed as a matchup of aces, but ultimately, this one was decided by the bullpens.
After the Red Sox failed to convert on some late-inning chances, the Texas Rangers cashed in in the bottom of the ninth, with Adrian Beltre singling to right, scoring Elvis Andrus from second base.
Clayton Mortensen, the fifth pitcher of the afternoon for the Red Sox, was tagged with the loss.
The Red Sox, who hadn't lost more than two in a row before Sunday, were swept in the three-game weekend series with Texas.
Neither Yu Darvish nor Jon Lester factored in the decision.
Darvish tied a season high with 14 strikesouts, registering at least one strikeout in each of his seven innings and striking out two or more in six of the seven frames.
The Red Sox used a two-run homer by David Ortiz in the first inning and a solo homer from catcher David Ross in the second to grab a 3-0 lead.
But Darvish allowed just one more hit from the third inning through the seventh -- a one-out single by Pedro Ciriaco in the fifth -- and finished with a flourish, striking out nine of the
final 13 Red Sox hitters he faced.
Lester, too, was sharp. Through five inning, he had allowed just one run on three hits. But he made a mistake to Nelson Cruz in the sixth and the Texas slugger drove it out for a game-tying two-run homer.
STAR OF THE GAME: Adrian Beltre
Beltre had just one hit in his first four plate appearances, but with the winning run in scoring position and two outs, Beltre came through with a game-winning single to give the Rangers the walk-off win in the bottom of the ninth.
HONORABLE MENTION: Yu Darvish
Darvish didn't factor in the decision ultimately, but it's hard not to be impressed with his seven-inning outing in which he struck out 14, tying a season-high.
GOAT OF THE GAME: Clayton Mortensen
Mortensen retired the first two hitters he faced in the ninth, then gave up a single, a wild pitch, an intentional walk, and finally, Beltre's game-winner.
TURNING POINT: In the top of the ninth, the Sox had runners at first and second and one out and couldn't score as Jarrod Saltalamacchia fanned and Jacoby Ellsbury rolled out to first.
BY THE NUMBERS: David Ortiz extended his hitting streak to 25 straight games.
QUOTE OF NOTE: "We've got a lot of professionals in here, and when you have a lot of professionals, you kind of say, 'Hey, there's 162 -- it happens.'" -- David Ross on how the Red Sox will handle their first three-game losing streak.