Buchholz scratched from Sunday start
Boston manager Bobby Valentine said Buchholz would likely be skipped and not pushed back. He said the right-hander was not with the team Saturday.
After a slow start, Buchholz has been Boston's best starter, going 4-0 with a 2.40 ERA in June. He was 3-1 in April, but had an 8.69 ERA.
The Red Sox said Aaron Cook will start Sunday.
Cook was placed on the 15-day disabled list on May 6 after suffering a left knee laceration when he was spiked covering home plate.
He made one rehab start with Triple-A Pawtucket on Monday, allowing three runs and seven hits in four innings, and was scheduled to make his second Saturday night before the Red Sox said he'd fill in for Buchholz.