Boston Red Sox pitcher Clay Buchholz will miss his scheduled start on Monday with a collarbone injury, manager John Farrell told reporters on Sunday.
Right-hander Alfredo Aceves will start in his place against the Philadelphia Phillies.
Buchholz began feeling pain in the AC joint of his right shoulder after his last start on Wednesday, according to The Boston Globe's Nick Cafardo. He is not scheduled to have an MRI, as Farrell said he expects the right-hander to make a start later in the week.
The team called the injury "irritation in right AC joint," according to CBSSports.com's Danny Knobler.
Buchholz, 28, has started the season 7-0 with a 1.73 ERA, while Aceves has posted an 8.20 ERA in six games, including three starts. Aceves returned to pitch a scoreless inning of relief on Friday after being sent down to Triple-A for a month.