Thielen (hamstring) took part in Tuesday's practice, Chris Tomasson of the St. Paul Pioneer Press reports.
After injuring his right hamstring Week 7, Thielen attempted to return Week 9 at Kansas City but lasted just seven offensive snaps before leaving the contest for good. He proceeded to focus on rehab rather than practice over the Vikings' ensuing two games, and with the benefit of the team's Week 12 bye, he appears to have made significant progress in his recovery. Tuesday's session was informal, though, so his activity level won't become clear until the release of Wednesday's injury report.