The Tigers placed Jansen on the 15-day injured list Thursday with pelvic inflammation.
Jansen underwent an MRI after exiting his appearance Wednesday with right groin tightness, and although he hasn't been diagnosed with a strain, the Tigers will send him to the injured list anyway to give him time to recover. Will Vest and Kyle Finnegan are the leading candidates to close games for Detroit while Jansen is sidelined, and Drew Sommers will come up from Triple-A Toledo to round out the big-league bullpen.