Grimm (back) threw a bullpen session Tuesday and is on the verge of going on a rehab assignment, Jeffrey Flanagan of MLB.com reports.

EDGE Analysis

Grimm may wind up throwing a live batting practice session within the next couple days before heading out on a rehab assignment. The right-hander isn't expected to need a lengthy rehab stint, and could return to the fold sometime next week if all goes according to plan.