Clay Buchholz will miss his scheduled start Sunday with an illness, manager Bobby Valentine said.
A replacement has not yet been named. Valentine said GM Ben Cherington is sorting through possible replacements.
From within the roster, the Sox could start Scott Atchison or Clayton Mortensen for a few innings. Doug Mathis is the scheduled started for Pawtucket tomorrow. Aaron Cook will start tonight for Pawtucket. Or at least so far he is.
Buchholz is 8-2 with a 5.53 ERA. Before giving up five runs on nine hits in his most recent outing, a 7-5 win over Miami on Tuesday, Buchholz was 3-0 with a 1.45 ERA in his four previous starts, striking out 28 and walking six.
Franklin Morales gets the start against the Braves on Saturday, his second replacement start since Josh Beckett went on the 15-day disabled list with right shoulder inflammation.
UPDATE: Nick Cafardo is reporting that Aaron Cook will be with the Sox tomorrow.
Cook was supposed to start Saturday for AAA Pawtucket. He has made one appearance for Boston this year, lasting just 2.2 innings and giving up seven runs on eight hits in a 8-2 loss against Baltimore on May 5. During that game, he suffered a gash on his leg when he collided with the Orioles' Chris Davis at the plate on a passed ball. The injury required 11 stitches and put Cook on the DL.
Cook is 3-0 with a 2.14 ERA in six starts for Pawtucket.
UPDATE II: The Sox have officially confirmed that Cook will start in Buchholz's place tomorrow.