"I'm pretty certain there's a DL at some point in time here," Melvin said. "There's corresponding moves and some other things that play into it as well. Those oblique injuries can be a little bit difficult, but we just want to make sure we process this thing and don't get ahead of ourselves, figure out what the coinciding move will be."
Colon had an MRI on Monday that confirmed the initial diagnosis, though the results still needed to be examined by Oakland's medical staff to determine the severity of the strain. The starter incurred the injury when he stopped to field a sacrifice bunt attempt by San Diego's Alexi Amarista.
While playing for Cleveland in 1999, Colon suffered a left oblique strain and missed 28 days, perhaps pointing to an extended absence with this injury.
Melvin said on Sunday that right-hander Tyson Ross, who has started 10 games this season for the A's and pitched well in a spot start on Saturday, could be called up from Triple-A Sacramento to replace Colon.