Lee is on the disabled list with a strained left elbow, but the Phillies hope he does not miss significant time. That might be wishful thinking, but in the meantime, Buchanan, who was one of the Phillies' bright spots in Spring Training, will pitch in his place.
The 25-year-old right-hander is 5-1 with a 3.98 ERA in nine starts with the IronPigs.
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.