Brett Lawrie hit the game's first pitch for one of Toronto's four homers and the Blue Jays tagged Jon Lester for a career-worst 11 runs in a 15-7 victory that completed a three-game sweep over the Boston Red Sox on Sunday.
J.P. Arencibia, Rajai Davis and Travis Snider also homered for the Blue Jays.
Toronto (48-47) posted a season high for runs and climbed out of the AL East cellar, moving a half-game ahead of the Red Sox (48-48). The Blue Jays matched their season high with 18 hits.
Lester (5-8) allowed a career-high four homers and nine hits. He was booed off the field after being pulled with no outs in the fifth.
Adrian Gonzalez hit a three-run homer and Jacoby Ellsbury a solo shot for the Red Sox, who play their next six games on the road against division leaders.
Boston opens a three-game series against AL West-leading Texas on Monday and has a three-game set versus the East-leading New York Yankees next weekend.
Henderson Alvarez (6-7) pitched 5 2-3 innings, giving up seven runs and seven hits.
Lawrie belted a 95 mph fastball completely out of Fenway Park over the Green Monster. Edwin Encarnacion and Davis sandwiched RBI doubles around Arencibia's run-scoring grounder, moving Toronto ahead 4-0. Jeff Mathis then laid down a safety squeeze, scoring Davis to make it 5-0.
Gonzalez hit a three-run homer in the bottom half, but the Blue Jays scored four more runs off Lester on consecutive homers by Arencibia and Davis in the second.
Arencibia hit a three-run shot into the Monster seats after Lawrie walked leading off and Encarnacion drew a two-out walk. Five pitches later, Davis homered into the first row of seats above the left-field wall. After Lester fanned Snider for the final out, he walked slowly to the dugout to loud boos.
Gonzalez homered about 10 rows into the bleachers behind Boston's bullpen.
Mike Aviles' sacrifice fly made it 9-3 before Snider, the last batter Lester faced, hit a two-run shot onto a black tarp that covers two sections of center-field seats during day games to help the hitters' background. Lester's ERA ballooned to 5.46 from 4.80.
In the sixth, Boston made it 11-7 on back-to-back RBI hits by Aviles and Nick Punto. Toronto added four more runs in the eighth.
The Red Sox finished a seven-game homestand 3-4 after taking three of four from the Chicago White Sox.