Mesa, AZ (Sports Network) - Chicago Cubs starting pitcher Mark Prior will be out of action for the next five-to-10 days because of an inflamed right Achilles' tendon.
Prior suffered the injury during drills last week and an MRI revealed no structural damage.
"He was in great shape when he got here," Cubs general manager Jim Hendry said. "We've just got to make sure he's 100 percent."
Prior, 18-6 with a 2.43 ERA in 2003, is entering his third big league season. He owns a 24-12 record in 49 major league starts.