Prior complained of soreness in his right shoulder before ever taking the mound Tuesday and was quickly shut down pending further review, which will come courtesy of Dr. Lewis Yocum. The Cubs are idle in Cactus League play Wednesday.
"(The shoulder) wasn't getting loose, so we weren't going to try it," pitching coach Larry Rothschild told reporters on Tuesday.
This is the third consecutive Spring Training in which Prior has been plagued by injuries. He spent months nursing an inflamed Achilles in 2004 that many later believed was a front to hide elbow discomfort.
In 2005, a sore pitching elbow kept him out of action during the first week of the season, and a line drive off the same elbow in late May in a game against Colorado sidelined him a month.
Prior threw 30 pitches to hitters this past Thursday and reportedly felt no discomfort. He was still being groomed to make his first scheduled start of the year April 5 at Cincinnati.