I guess it’s from throwing, and I get work in that area a lot," Nola said of the injury. "I’m not really sure,” he said. “I’ve never had a stress fracture in my rib before."

Nola had already been out since early May with a sprained right ankle that was progressing more slowly than expected.

Philadelphia Phillies starter Aaron Nola, who hasn't pitched since May 14 due to a right ankle sprain, could be out for another month after tests revealed a separate rib injury.