Milwaukee's Shaun Marcum, who would have made the start, is battling elbow tightness, while Toronto has a cavalcade of pitchers making their way to the disabled list.
Jesse Chavez, who was called up from Triple-A Las Vegas on Monday, will take the mound for the Blue Jays. He posted a 7-2 mark in the Pacific Coast League with a 3.84 ERA.
Toronto manager John Farrell said with all the injuries surrounding the rotation, he may be more inclined to go to his bullpen.
"We'll probably take a little bit different approach with the use of our relievers, and that may mean more multiple inning outings with an extra day of rest in between," Farrell said.
Tyler Thornburg, one of Milwaukee's top prospects who's off to a great start for the Huntsville Stars, will oppose Chavez.
In 13 starts, Thornburg -- who was scheduled to pitch in the Southern League All-Star Game on Tuesday -- is 8-1 with a 3.00 ERA and 71 strikeouts.
Blue Jays: Drabek to undergo second Tommy John surgery
One pitcher who won't be returning to the Toronto rotation this season is Kyle Drabek. Farrell said Monday the righty will undergo the second Tommy John surgery of his career.
The surgery will be performed by renowned surgeon Dr. James Andrews in Pensacola, Fla. His previous procedure was in 2006, when he was still in high school.
Drabek was 4-7 on the season with a 4.67 ERA.
Brewers: Ramirez hitting stride
Milwaukee third baseman Aramis Ramirez had perhaps his best game since joining the Brewers when he went 3-for-3 with three RBIs, a homer and a double on Monday.
Ramirez has now hit safely in eight of the past 10 games and has five multi-hit games during the stretch. He is hitting .262 with eight dingers and 38 RBIs on the season.
Blue Jays third baseman Brett Lawrie, a 2008 Draft pick of the Brewers, faced his former organization in the series opener Monday. He went 2-for-5 with a home run, a double and three runs.
Blue Jays southpaw Evan Crawford was optioned to Triple-A Las Vegas to make a roster space available for Chavez.