SAN FRANCISCO -- Left-hander Cole Hamels will test his left oblique injury Tuesday when he makes an injury rehabilitation start for the Cubs' Triple-A Iowa affiliate against San Antonio.

Hamels is expected to throw approximately 40 to 50 pitches. Obviously, how the 162-game winner handles this test will go a long way toward helping the Cubs determine what to do next with him.

Hamels, 6-3 with a 2.98 ERA, hasn't appeared in a regular-season game since June 28 at Cincinnati, one day before he went on the injured list.

"Hopefully it's going to be sooner rather than later," Cubs manager Joe Maddon said, referring to Hamels' recovery. "After he throws, we'll know more."

Edwards out: The Cubs optioned right-hander Carl Edwards Jr. to Iowa, hoping the reliever can harness his considerable talent.

Edwards, 27, was 1-1 with a 5.87 ERA in 20 appearances for Chicago. Opponents batted .151 off him, but Maddon didn't like what he saw Sunday when Edwards allowed a run and hit a batter in one-third of an inning against San Diego.

Maddon remained convinced that Edwards possesses good stuff. But, Maddon added, "there's something wrong. And he has to find it. For him to be as good as he can be, he needs to get it right."

Rowan Wick was summoned from Iowa to fill Edwards' bullpen spot.

Contreras closer: Catcher Willson Contreras (right foot strain) increased the intensity of his baseball-related activities Monday, indicating he could be reinstated from the injured list Wednesday, when he's eligible.

That would prompt another decision for the Cubs: whether to operate with a three-man catching contingent by adding Contreras to the duo of Martin Maldonado and Victor Caratini, or to stick with the usual two-man contingent and drop either Maldonado or Caratini.