Boxberger (back) threw a 20-pitch batting practice session Monday and is likely to throw another Thursday, Marc Topkin of the Tampa Bay Times reports.
The veteran reliever got through his session without a hitch, and if he's able to enjoy a successful encore Thursday, he could start a rehab assignment at some point next week. That pace would keep Boxberger on track for his stated goal of making his 2017 big-league debut by mid-June.