Cincinnati used five relievers while squandering an eight-run lead during a 14-9 loss in the series opener on Friday, the second-biggest comeback in Blue Jays history. Reliever Jumbo Diaz made his big league debut in the seventh inning and gave up two homers.
Contreras also will make his major league debut. He went 2-1 with a 2.70 ERA in nine games for Double-A Pensacola.
Outfielder Roger Bernadina was designated for assignment to open a spot. Bernadina is batting .153 with no homers and five RBIs in 44 games. The Reds also designated Bernadina for assignment last May, then brought him back three days later.