On Tuesday, manager Bobby Valentine said Padilla had triceps/biceps/groin issues. He narrowed that to a biceps issue Wednesday. Padilla has not pitched since giving up two home runs in the ninth inning of Sunday's 6-4 win over the Minnesota Twins.
Taking his place on the roster was reliever Clayton Mortensen.
"Padilla has a little soreness in his biceps," Valentine said. "Probably could pitch on Friday, but we just aren't willing to take the chance of going short the next couple of days. It's not fair to the guys who are out there. It could put us in a real bind."
This is the fifth time Mortensen, who has options, has been called up from Pawtucket. The last two times, he lasted just one day each. On July 7, he was the "26th man" for a day-night doubleheader and returned to Pawtucket the next day. On July 31, he was called up and went back the next day when Craig Breslow was added to the roster after being acquired from Arizona.