Manoah was placed on the 10-day injured list Monday after he slipped and fell down rain-soaked dugout steps at Sahlen Field in Buffalo and bruised his back.
Manoah, Toronto's first-round pick (11th overall) in the 2019 MLB Draft, has been a revelation in his first big-league season, compiling a 2-1 record with a 2.90 ERA and 52 strikeouts across 40.1 innings.
Per Montoyo, Thomas Hatch will pitch Monday if Manoah isn't ready as the Blue Jays kick off a four-game set vs. the Red Sox.
Meanwhile, Toronto will hand the ball to Steven Matz, Hyun Jin Ryu, Ross Stripling this weekend vs. New York Mets.
The Blue Jays also announced Wednesday that they've recalled right-hander Patrick Murphy from triple-A Buffalo and he will be active for tonight’s series closer vs. the Red Sox.