Toronto right-hander Brandon Morrow will start the regular season on the disabled list because of inflammation in his forearm.
The Blue Jays announced the decision before Wednesday night's game against the New York Yankees.
Toronto manager John Farrell is hopeful Morrow will return by mid-April.
Morrow felt discomfort after his last bullpen session, and was scratched from his scheduled start in a minor league game Wednesday.
"It's to make sure that we do what's right for him and make sure this doesn't become more of an issue," Farrell said. "Put him on the disabled list to be able to make sure we take the appropriate steps to get him back."
"We now have five guys that we know are going to be in the rotation," Farrell said. "It's a starting point."
Toronto reliever Frank Francisco, out with a right pectoral muscle injury, will also started the regular season on the DL. The closer will resume a throwing program on Sunday.
"Giving it a chance to settle down," Farrell said.
Also, the Blue Jays sent promising third baseman Brett Lawrie to their minor league camp.