Morrow (biceps) is scheduled to throw off a mound Sunday, Jesse Rogers of ESPN.com reports.

EDGE Analysis

This is a positive step for Morrow, who hasn't thrown a bullpen session since suffering a setback in mid-August. Manager Joe Maddon said Wednesday that there was "barely" enough time for Morrow to return this season, but the Cubs are now hoping to have the right-hander back in game action sometime between Sept. 14-16 if everything goes as planned. Assuming he gets through Sunday's session setback-free, Morrow will progress to a simulated game before potentially returning. Once (and if) he's activated, he isn't expected to immediately resume closing duties.