He was scratched from Saturday's start against the Los Angeles Angels after an MRI showed that the tibialis tendon behind his right ankle was torn.
The right-hander will remain in a walking boot for approximately four weeks and re-evaluated in two weeks before it can be determined how much time he will eventually miss.
Peavy, the 2007 NL Cy Young winner, is 3-1 with a 4.43 ERA in four starts since he voided a trade to the Chicago White Sox. The injury occurred while he ran the bases in his first start after the proposed trade.
(Copyright 2009 by The Associated Press. All Rights Reserved.)