It'll be the first time Fister has thrown off a mound since last week in Kansas City, where he felt pain again in that left side while throwing on back-to-back days. Since then, the Tigers have been relatively cautious about his progress to avoid a more severe setback, though manager Jim Leyland sounded upbeat after Fister underwent treatment on Monday.
Thursday's mound session won't put him on a timetable to return to game action by the end of the month, but it at least puts a return in sight. Adam Wilk made his third start in Fister's place on Wednesday night against the Mariners.
"It's kind of a wait-and-see thing," manager Jim Leyland said Wednesday afternoon.