Toronto Blue Jays right-hander Josh Johnson missed his scheduled start on Friday against the New York Yankees because of tightness in his right triceps.
The Blue Jays said it was a precautionary move, and he has not been placed on the disable list yet. The extent of the injury is not known.
Left-hander Aaron Laffey replaced Johnson as the team's starter on Friday.
Johnson, 29, has allowed at least four runs in all but one of his April starts. He is 0-1 with a 6.86 ERA in four starts this season.