August 17. 2017 12:52AM

Red Sox stun Cardinals with Betts' walk-off double

The Sports Xchange

Boston's Jackie Bradley Jr. dives into home plate for the winning run against the St. Louis Cardinals in the ninth inning of Wednesday's game at Fenway Park. (David Butler II-USA TODAY Sports)

BOSTON — Mookie Betts ripped a two-run double off the Green Monster to cap a three-run, ninth-inning rally and give the Boston Red Sox a 5-4 victory over the St. Louis Cardinals on Wednesday night.

Betts, who drove in a run earlier in the game, hit a 3-2 pitch from Boston native John Brebbia off the left field wall, scoring pinch runner Chris Young and Jackie Bradley Jr.

Bradley scored from first and likely would have been out at the plate, but catcher Yadier Molina couldn’t hold onto the throw from shortstop Paul DeJong.

The win, which completed a four-game Boston sweep of the Cardinals this season, lifted the Red Sox to 3-48 this season when trailing after eight innings and kept them 4 1/2 games ahead of the New York Yankees in the American League East.

The Red Sox have won 12 of their past 14 games.

The Cardinals have lost three straight following an eight-game winning streak.

Trevor Rosenthal started the ninth with a 4-2 lead and gave up a leadoff homer to Xander Bogaerts before walking Mitch Moreland on a 3-2 pitch that bounced to the backstop. Zach Duke (0-1) came on and struck out pinch hitter Brock Holt on a 3-2 pitch after falling behind 3-0, then went 3-0 on Bradley before walking him at 3-2.

Brebbia came on, and with the count 0-2 on Eduardo Nunez, the pitcher held the set too long, and plate umpire Chris Segal called time. That got Molina upset, and manager Mike Matheny came out. Matheny, still fuming over a check-swing call earlier in the inning, was ejected by Segal.

Nunez fouled out before Betts delivered against Brebbia, who grew up a Red Sox fan.

Boston closer Craig Kimbrel (5-0), who hadn’t pitched since Sunday, threw a perfect ninth inning.

St. Louis starter Lance Lynn allowed two runs (one earned) in six innings. He hasn’t lost since July 4.

The Cardinals collected five hits in scoring all four of their runs in the second inning off Eduardo Rodriguez, who is 0-1 with a 4.78 ERA in six starts since coming off the disabled list and hasn’t won since May 26.

Kolton Wong had three hits, an RBI and a run for the Cardinals.

The second inning was wild, with Bradley twice trying to nail a runner trying to score from third base on a single. He was successful the second time, throwing out Matt Carpenter.

Wong, after bunting foul twice in attempts to sacrifice, singled a run home, and Luke Voit made it 2-0 with an RBI single. The third run scored on a passed ball by catcher Christian Vazquez, and the fourth came in when Carpenter dropped his single in front of Bradley.

However, Carpenter was eventually thrown out trying to score from third after Tommy Pham’s single to center.

As Rodriguez settled down, the Red Sox took advantage of a Lynn throwing error to cut their deficit in half in the third.

The first run scored when Nunez hit a ball back to Lynn for an infield single, but Lynn threw the ball away allowing Vazquez to score all the way from second. Betts then made it 4-2 with a sacrifice fly.

Rodriguez allowed four runs on eight hits in 5 1/3 innings.

NOTES: Carl Yastrzemski, Jim Lonborg, Ken Harrelson, Rico Petrocelli and Reggie Smith headed the list of members of the 1967 Red Sox “Impossible Dream” team honored prior to the game. ... The Red Sox will pitch LHPs Drew Pomeranz and Chris Sale on Friday and Saturday against the New York Yankees but still hadn’t decided between RHPs Rick Porcello (on regular rest) and Doug Fister for Sunday. ... Boston will honor broadcaster Jerry Remy, battling cancer for the fifth time, and his 30 years in the TV booth Sunday. He will throw out the first pitch. ... Boston LHP David Price (elbow) delayed a throwing session a day and will throw Thursday from flat ground. ... The Cardinals visit the Pirates this weekend for three games, the first two in Pittsburgh and the third, on Sunday night, in a small minor league stadium in Williamsport, Pa.