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.
The Blue Jays also added a reliever for the second game of the series, calling up left-hander Rob Rasmussen for the second time this season.
Rasmussen didn't have a decision during his four appearances in May, when he gave up two hits and no runs in two innings.
Toronto used five relievers Friday night. Liam Hendriks started and lasted only 1 2-3 innings, giving up six hits and six runs.
Hendriks was optioned back to Triple-A Buffalo as planned. The Blue Jays had called him up to start in place of R.A. Dickey, who was pushed back to Sunday to let his sore groin heal.