Dublin - Memorial Tournament winners Ernie Els, Jim Furyk, Justin Rose and Vijay Singh have each committed to play in the 37th tournament, set for next week at Jack Nicklaus' Muirfield Village Golf Club.
The tournament also announced that Luke Donald was coming to play and that Bo Hoag will receive an exemption to play in the field.
Donald's presence gives the tournament nine of the top 10 players in the world rankings.
Els won the Memorial in 2004, Furyk in 2002, Rose two years ago and Singh in 1997.
Hoag will be making his first appearance at the Memorial. He will be playing in his second PGA Tour event this season after missing the cut at the Honda Classic.