An MRI Wednesday morning revealed a sprained sternoclavicular joint, which connects the clavicle to the sternum.
"I guess we're going to take it day to day," Span said. "It's going to be painful. It's kind of just going to be based on how I feel. There's going to be days when I can go out there and swing, and there's going to be bad days."
Ben Revere took over Span's normal posts as leadoff hitter and center fielder in Wednesday's game against the Mariners. Chris Parmelee started in right field.
Span said he will be treated with anti-inflammatories, but the injury will likely nag at him for the remainder of the season.
"I don't think there's really much I can really do," Span said. "They said it takes four to six weeks for it to heal -- if I just did nothing. But they don't seem to think me continuing to try to swing will make it worse. So hopefully get on this anti-inflammatory and get some more treatment, then maybe it'll be more bearable for me to at least play."