BOSTON — Brandon Valenzuela hit a go-ahead RBI double off Aroldis Chapman with two outs in the ninth inning and the Toronto Blue Jays completed a three-game sweep of the Boston Red Sox with a 4-3 win Thursday.

Valenzuela’s tiebreaking hit clanked off the Green Monster and came after Red Sox catcher Connor Wong misplayed a pop-up in foul territory that would have been the final out of the ninth.

Vladimir Guerrero Jr. and Nathan Lukes homered for Toronto, which has taken five of six against Boston this season.

Trailing 3-1, the Red Sox tied it in the eighth on back-to-back homers by Isiah Kiner-Falefa and Caleb Durbin.

Tommy Nance (1-2) picked up the win after recording the final two outs in the eighth and Mason Fluharty pitched a perfect ninth for his first save of the season.

Chapman (0-2) took the loss as Boston fell to 12-25 at Fenway Park and 6-17 against AL East teams this season.

Guerrero jumped on the first pitch he saw from Red Sox starter Sonny Gray for a 410-foot homer that landed in the first row of the Green Monster seats. It was his fourth home run of the season and first since May 17.

Toronto starter Trey Yesavage carried a shutout into the seventh, but left with the game tied at 3. The right-hander struck out six and walked none while allowing three runs in 7 1/3 innings.

Gray also allowed three runs – including solo homers by Guerrero and Lukes — and six hits over seven innings. The right-hander struck out seven and walked one.

Before the consecutive homers by Kiner-Falefa and Durbin in the eighth, the Red Sox snapped a 16-inning scoreless streak in the seventh when Wilson Contreras drove in Ceddanne Rafaela with a grounder.

Blue Jays: Right-hander Kevin Gausman (4-4, 3.41 ERA) starts Friday at Wrigley Field against Chicago right-hander Ben Brown (3-2, 1.74).

Red Sox: Travel to Seattle for a weekend series that begins Friday night. Boston left-hander Ranger Suarez (2-3, 3.21) starts opposite Seattle right-hander Bryce Miller (3-0, 1.54).