The Blue Jays matched a season high with three errors, two of which led to runs Sunday in a 4-3 loss to the last-place Boston Red Sox.
"We've been playing outstanding defense, so we were due for a clunker like this," said pitcher Mark Buehrle, a four-time Gold Glover whose errant relay throw in fourth inning led to Boston's first run. "We've just got to come back tomorrow and be ready for the Yankees."
In the eighth, Pablo Sandoval came home on Bradley's sacrifice fly after reaching on a fielding error by reliever Brett Cecil.
Center fielder Kevin Pillar made an accurate throw to the plate on Bradley's fly ball, but the short hop skipped past catcher Dioner Navarro as Sandoval scored standing up.
"Unfortunately, a lot of things didn't go our way," Navarro said. "But we've got to go through that adversity. We'll be all right. We're right where we want to be."
Toronto began the day with a 3½-game lead over the Yankees, who played at night against the Mets. The Blue Jays now host the Yankees in a three-game series.
The Red Sox went into the weekend in last place and took two of three at Rogers Centre. Boston rallied from an early 3-0 deficit in the wrapup, handing Toronto just its third series defeat since July 30.
"New York is a new team," Navarro said. "We're just trying to win every series we get."
Rich Hill (1-0) struck out 10 in his first big league win since July 14, 2013, when he pitched in relief for Cleveland.
Hill gave up three runs and seven hits in seven innings. He walked none and was one shy of his career high for strikeouts.
"I can't say enough about what he did," interim manager Torey Luvullo said.
Hill, who fanned 10 at Tampa Bay last week, became the first pitcher in Red Sox history to strike out at least 10 in each of his first two Boston starts.
"He's been really special these past two outings," Bradley Jr. said. "It's fun playing behind him, that's for sure."
It was 3-all when Cecil (3-5) couldn't field Sandoval's short grounder to open the eighth. Mark Lowe came in to pitch and Sandoval took second on a groundout and then moved to third on Sandy Leon's single.
Lovullo acknowledged that Boston was fortunate to take the lead when Pillar's throw eluded Navarro.
"I think we got lucky," Lovullo said. "They executed the throw pretty well but they didn't catch it."
The unearned run snapped Cecil's scoreless innings streak at 26. He hadn't allowed a run since June 21 against Baltimore.
Noe Ramirez worked the eighth and Robbie Ross Jr. finished for his fourth save and second in two days. Ross struck out pinch-hitter Justin Smoak to end it, stranding the tying run at second.
Navarro hit a two-run homer in the second and Ben Revere added an RBI single later in the inning.
Xander Bogaerts hustled to score in the Boston fourth. Running from first on an infield grounder by David Ortiz, Bogaerts kept going to third when it was left unguarded by the shift, then scored when Buehrle threw past third baseman Josh Donaldson.
The Red Sox tied it on a two-out, bases-loaded single by Travis Shaw in the fifth, an inning that was prolonged when Toronto couldn't turn a double play on Mookie Betts' grounder to short. Second baseman Cliff Pennington's relay throw pulled Chris Colabello off the bag at first. Four batters later, Shaw delivered the tying single.
Buehrle, who has won just once in six starts, allowed three runs and eight hits in six innings.
ONE RUN WOES
The Blue Jays are 13-27 in one-run games
Red Sox: Sandoval returned after missing the previous two games with an illness but left suffering from lightheadedness after scoring the go-ahead run.
Red Sox: Boston returns home Monday to begin a four-game series with Tampa Bay. LHP Eduardo Rodriguez (9-6, 3.94 ERA) starts the opener against Rays RHP Chris Archer (12-12, 2.95). Rodriguez is 3-1 with a 1.72 ERA in his past five starts.
Blue Jays: LHP David Price (16-5, 2.42 ERA) starts the opener of a three-game series against the Yankees. RHP Adam Warren (6-6, 3.33) starts for New York. Price is 3-0 with a 1.89 ERA in his past three starts.