Red Sox pitcher Clay Buchholz will not make his scheduled start Sunday against the Red Sox due to an illness, manager Bobby Valentine announced Saturday.

Pitcher Aaron Cook is expected to come off the disabled list and make the start on Sunday for Boston. In one start this season, Cook allowed seven runs -- six earned -- in 2 2/3 innings before leaving with a left knee laceration.

Valentine said that he expects Boston to skip Buccholz's start entirely rather than push it back.

This season, Buchholz is 8-2 with a 5.53 earned run average. However, Buchholz is 4-0 with a 2.40 ERA in June.