Reigning British Open Champion Phil Mickelson has withdrawn from the Grand Slam of Golf due to a scheduling conflict, the PGA of America announced on Tuesday.
Mickelson will be replaced in the field by Padraig Harrington, who won the event last year.
Harrington will also take Mickelson's place in the foursome of this year's major winners, joining Masters champion Adam Scott, U.S. Open champion Justin Rose and PGA champion Jason Dufner.
Scott, Rose and Dufner are each making their first appearance at this event, while Harrington is in the field for the fourth time, adding a pair of runner- up finishes in 2007 and 2008 to his victory last year.
The defending champion of the Grand Slam of Golf receives the initial invitation if a current major champion is unable to compete; then the Major Champions Points list, which charts the performance throughout the year of active major champions, is used to complete the field.
The 36-hole event will take place from Oct. 14-16 at Port Royal Golf Course in Bermuda.