Josh Donaldson homered and drove in three runs, powering the Toronto Blue Jays past the AL East-leading Boston Red Sox 6-4 on Monday night.
Boston's six-game winning streak was snapped and its magic number to clinch a second straight division title remained at three. The Red Sox lead the second-place New York Yankees, who beat Kansas City earlier in the day, by four games with six remaining.
Eduardo Nunez and Mookie Betts both left with injuries for Boston. Nunez aggravated a right knee injury that sidelined him for 13 games, and Betts came out with pain in his left wrist.
Ryan Goins hit a solo homer and Teoscar Hernandez had a two-run double for the Blue Jays. Brett Anderson (2-2) allowed three runs in five innings.
Red Sox lefty Drew Pomeranz (16-6) had his shortest start of the season, giving up five runs and seven hits in two innings. He had only lost once in his last 18 outings, holding opponents to three runs or fewer in 16 of those games.
Betts drove in two runs for the Red Sox, going over the 100-RBI mark for the second consecutive season. Andrew Benintendi had a pinch-hit solo homer.
Roberto Osuna got three outs for his 38th save.
Toronto slugger Jose Bautista was ejected by plate umpire Chad Fairchild after getting called out on strikes.
Coming off an 8-1 road trip that helped them maintain control of the AL East, the Red Sox fell into a hole early.
The Blue Jays chased Pomeranz with four runs in the second to take a 5-2 lead when Hernandez and Donaldson each hit a two-run double.
Donaldson homered about a third of the way up a light stanchion in left-centre in the first.
Red Sox: Nunez fouled off a pitch his second time up and went to the ground in pain. He finished the at-bat with a lineout to third, but barely got out of the box and was unable to put much weight on his knee. . Betts grabbed his left hand in pain after a bloop single and pointed at it while talking with a trainer.
The 24-year-old Betts has 101 RBIs and 98 runs scored this season. Last year, the right fielder drove in 113 and scored 122. The only other Red Sox player with multiple 100/100 seasons before turning 25 was Hall of Famer Ted Williams from 1939-42.
Blue Jays: LHP J.A. Happ (9-11, 3.64 ERA) is set to pitch the second game of the series Tuesday night. He lost his last start Thursday after winning the previous three.
Red Sox: LHP Chris Sale (17-7, 2.75) takes his major league-leading 300 strikeouts to the mound. Sale appears to be in a close race with Cleveland ace Corey Kluber for the AL Cy Young Award.