Vodnik (biceps) threw a 15-pitch bullpen session Saturday, Patrick Lyons of JustBaseball.com reports.
Vodnik was only able to throw at about 80 percent intensity, though it's still a step in the right direction, as it marks the first time he's thrown off a mound since landing on the injured list Aug. 21. The 24-year-old righty will be eligible for activation Tuesday, but the Rockies will likely look to have him face live hitters before clearing him to return.