 On March 22, Marcum was named the Opening Day starter for the 2010 season, succeeding Roy Halladay for that role, who had seven consecutive opening day starts for the team from 2003 to 2009.On May 2, Marcum got his first win against the Oakland Athletics, it was his first win since September 11, 2008 before going through Tommy John surgery.On August 4, 2010, Marcum gave up Alex Rodriguez's 600th career home run.