The Red Sox took sole possession of fourth place in the division for the first time and have won 16 of their past 22 games. After starting the season 12-19, Boston has been among the hottest teams in baseball.
The Blue Jays, meanwhile, have dropped two straight after sweeping the Orioles to kick off their six-game homestand and sit alone in last place in the East despite a 27-26 record.
Toronto will look to get back on track with rookie starter Drew Hutchison for the finale.
Hutchison, 21, is coming off the best performance of his young career, throwing seven innings and striking out nine (both career highs) against Baltimore.
"I think he found something out about himself last night, just with his intensity and use of his lower half in his legs that really created some additional velocity, and what's really impressive is that he carried it through the seven innings," Blue Jays manager John Farrell said.
"[There may be] a little bit of an adjustment in his own attitude, the way he attacked brought out more power. When you look at it, his fastball graded out two grades better. I think he found something out about himself last night."
Hutchison, whose average fastball is 91 mph, was able to crank his fastball up to 95 in that start. On Sunday he will be opposed by Daniel Bard, who has made a career of throwing mid-to-upper-90s fastballs.
Bard, a winner of three of his last four decisions, including his most recent start, against the Tigers, will look to put an end to his struggles against the Blue Jays.
The right-hander enters Sunday's start with an 0-3 record and 4.91 ERA in 22 games -- one start -- versus the Blue Jays. He faced them earlier in the season, in his first career start, and took the loss, but he is happy with how he's progressing.
"[I'm] just staying in my delivery better," Bard said about the adjustments he has made. "I made a couple of tweaks, nothing major, but just a couple of things to keep everything on time, to keep my arm in the same slot. I made those tweaks in my side session three days ago and felt really good about it coming out of that."
Red Sox: Leading the way
Boston increased its Major League-leading RBI total from the leadoff spot in Saturday's win over Toronto.
The Red Sox entered the game with 37 RBIs from their No. 1 hitters and got two more on a single by Daniel Nava in the second inning.
Boston also entered Saturday with the most extra-base hits in the Majors, with 207, and tacked on three.
Nick Punto hit a double as well as his first home run of the season -- an upper-deck shot to right -- in Saturday's 7-4 win.
They were Punto's first extra-base hits since he recorded a double his second game of the season.
Blue Jays: Power combo
Jeff Mathis hit his third home run of the season in the third inning of Saturday's loss, giving Blue Jays catchers the American League-lead, with 12.
Toronto entered the contest tied with Boston for homers out of the catching spot, as starter J.P. Arencibia has chipped in nine.
The Blue Jays had scored seven straight runs off solo home runs before Kelly Johnson hit an RBI single in the fourth inning of Saturday's loss.
Toronto has hit a a homer in 15 of its past 17 games and was tied for second in the Majors at the conclusion of its game, with 76. The Yankees lead the Majors, with 78.