In Saturday's 5-4 win on Saturday, Bellinger set up the winning rally in the ninth inning with a leadoff double against Toronto reliever Jordan Hicks. He scored on Christopher Morel's tie-breaking double. Bellinger also had an RBI single in the fourth inning and rode home on Dansby Swanson's three-run homer.
Bellinger hit a two-run home run among his two hits on Friday to help the Cubs win the opener 6-2.
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Over his past 43 games, Bellinger is batting .411 (67-for-163) with nine doubles, 11 homers, and 37 RBIs.
"Belli has been our most valuable player," Cubs manager David Ross said. "That leadoff double was huge."
"Bellinger is probably the best hitter in the game for the last two months," Blue Jays manager John Schneider said. "They've got power, they've got speed, they've got guys that are above average in a lot of different ways. They're scoring a ton of runs right now. They're a hot team."
Bellinger said, "One through nine, we have a really, really deep lineup. It doesn't matter if it's the heart of the order, the bottom of the order. We've got a bunch of guys that can get the job done."
Morel's go-ahead double gave him his team-leading eighth RBI in the ninth inning this season. He is hitting .311 (23-for-74) with 38 RBIs with runners in scoring position this season.
Swanson has six home runs and 14 RBIs in his past 12 games.
Right-hander Jameson Taillon (7-6, 5.17 ERA) is scheduled to start for the Cubs on Sunday. He is 5-4 with a 3.54 ERA in 10 career starts against the Blue Jays.
Left-hander Hyun Jin Ryu (0-1, 4.00) is scheduled to start for the Blue Jays. In four career starts against the Cubs, he is 1-1 with a 3.00 ERA.
The Blue Jays had a two-run home run from Whit Merrifield on Saturday, and the left fielder continued to play superbly on defense.
Merrifield has 11 home runs for the season, matching his total from last season in 29 fewer games. In his past 32 games, he is hitting .333 (42-for-126) with three doubles, nine home runs, and 23 RBIs.
Merrifield has been one of the few consistent hitters for the Blue Jays, who have lost three in a row.
The Cubs, meanwhile, feel good about their push for a postseason berth.
"Me and a few other guys in here have been in it 'til the end a few times and understand what it takes," Bellinger said. "Overall, the group of guys in here are really intelligent, really smart baseball players. They really know how to take care of the body. And even if they haven't been there before, we trust the guys that they're going to be able to handle it."
Former Toronto slugger Jose Bautista was added to the Blue Jays' Level of Excellence in a pregame ceremony Saturday.
Toronto put right-hander Hagen Danner (left oblique strain) on the injured list Saturday and recalled right-hander Nate Pearson from Triple-A Buffalo.