Jansen sustained the injury in the sixth inning of Friday's 13-9 win over the host Colorado Rockies.
Jansen took a foul ball off his throwing hand. He'd hit a two-run homer to break a 2-2 tie in the top of the inning.
Tyler Heineman was recalled from triple-A Buffalo for Saturday's second-game of a three-game set in Denver.
The 32-year-old has appeared in nine games for the Jays this season after Toronto acquired him April 30 from Pittsburgh.
Heineman compiled five hits, including a double, and scored a run in 16 at bats.
Toronto (74-61) is chasing the Texas Rangers for an American League wild-card spot.
This report by The Canadian Press was first published Sept. 2, 2023.
The Canadian Press