Germano takes the spot of left-hander Aaron Laffey, who was designated for assignment after he surrendered a pair of runs and walked five batters during his start on Friday.
"He'll be coming out of the 'pen if we get into trouble early," manager John Gibbons said of Germano, who was originally scheduled to start for Triple-A Buffalo on Saturday.
Relievers Aaron Loup, Brad Lincoln and Steve Delabar were all unavailable for Saturday's game. Veteran lefty Darren Oliver also pitched on Friday and ideally wouldn't have to be used on back-to-back days, which left only Esmil Rogers, Brett Cecil and closer Casey Janssen as the available fresh arms prior to Germano's arrival.
The extended workload for the bullpen has been an ongoing storyline through the first month of the season. Entering Saturday, Toronto's relievers had been forced to throw 87 innings this year, which trails only the Astros for most in the American League.
A lot of the blame for Saturday's issues rests on Laffey. The 28-year-old got through the first two innings of his start on Friday relatively OK but seemed incapable of finding the strike zone during the third frame.
Laffey managed to throw just 23 of his 55 pitches for strikes, as a result, he was cut from the team just a few days after being claimed off waivers.
"He'll throw strikes," Gibbons said of Germano. "If you get hit, it's one thing. If you start walking the world, you can't lose that way."
Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB. This story was not subject to the approval of Major League Baseball or its clubs.