Bautista hadn't started since leaving a June 22 loss at Cincinnati with a strained hamstring before homering in his first at-bat in Tuesday's 4-1 victory. Colby Rasmus also went deep as the Blue Jays avoided a season worst-tying fourth consecutive defeat and improved to 8-15 in their last 23 games.
Toronto (46-39) is trying to hold off Baltimore and New York for first place in the AL East.
"Obviously, adding a guy like Bautista helps," Tuesday's losing pitcher Marco Estrada said. "He's one of the better hitters in the game."
Despite Estrada's praise, Bautista is 2 for 14 in his last six games. Baseball's leading All-Star vote-getter was the designated hitter but could return to right field Wednesday.
The NL Central-leading Brewers (51-34) are on the verge of losing three straight for the first time since a season-worst four-game skid May 17-20. Ryan Braun drove in a run Tuesday, giving him eight RBIs over a six-game stretch.
Milwaukee will try to bounce back behind Wily Peralta (9-5, 3.20 ERA), who has won a career-best five consecutive starts despite a 4.22 ERA. The right-hander has been backed by an average of 8.16 runs during his winning streak, and he saw that trend continue in Thursday's 7-4 victory over Colorado.
Peralta, who blew a three-run first-inning lead before getting it back in the fifth, allowed four runs, eight hits and two walks over six innings.
"He can pitch better," manager Ron Roenicke said. ''He's not locked in. He's still making good pitches, but he's struggling to get through the lineups."
This marks Peralta's first appearance against the Blue Jays. He is 1-0 despite a 5.40 ERA in two interleague starts this year.
Toronto counters with J.A. Happ (7-4, 4.29), who struck out a season-high eight over 7 2-3 innings of four-hit ball in Thursday's 7-0 victory over the Chicago White Sox. The left-hander bounced back after surrendering a career high-tying eight runs over four innings in an 11-1 loss at Cincinnati on June 21.
"I think some things are more crisp than others on different days," he told MLB's official website. "It's trying to get at least two pitches, ideally three, when you have four, it becomes easier, but it's tough to have command of all of those at all times. I think it's about going out and being aggressive with whatever you've got that day."
Happ is 3-3 with a 5.93 ERA in nine games - eight starts - against the Brewers, last facing them in 2012 with Houston. Rickie Weeks is 7 for 14 with two homers and two doubles in their matchups, but Mark Reynolds is 0 for 16 with eight strikeouts.
Milwaukee's Khris Davis exited with a strained pectoral muscle Tuesday, leaving his status for this game unclear. Davis leads the club with 14 homers.
The Brewers have won 11 of the last 14 in this series.