The Blue Jays placed Kirk on the 10-day injured list Saturday with a left thumb fracture, Hazel Mae of Sportsnet reports.
Kirk took a foul tip off his left thumb while catching in the 10th inning of Friday's contest. He doesn't have a return timeline in place yet, per Mae, but some clarity should come after he visits a doctor Monday to determine whether surgery is required. In the meantime, Tyler Heineman will take over as Toronto's starting catcher, and Brandon Valenzuela will come up from Triple-A Buffalo to provide depth.