De Leon tossed just two pitches Monday in his Grapefruit League appearance against the Tigers before departing with an apparent right arm injury, Chris McCosky of The Detroit News reports.
The Blue Jays will likely send De Leon in for X-rays and possibly an MRI before providing a diagnosis of his injury, but he looked to be in considerable pain while bouncing a pitch to home plate during Monday's appearance. De Leon is attending big-league camp as a non-roster invitee and is hoping to win a spot in Toronto's Opening Day bullpen.