The three will join tournament host Steve Stricker, Jerry Kelly, Scott McCarron and Kirk Triplett, who earlier made commitments. The full 78-player field for the championship will be set June 14.
Clarke, of Northern Ireland, is best known for his victory at the 2011 Open Championship at Royal St. George’s in England. The veteran of the European Tour and PGA TOUR has 21 tournament wins worldwide.
Goosen, of South Africa, will be enshrined into the World Golf Hall of Fame in June. He’s a two-time major champion, winning the U.S. Open in 2001 and 2007.
DeMarco won three times on the PGA Tour. He is perhaps best known for his final-round battle with Tiger Woods in the 2005 Masters, where Woods outlasted him in a sudden death playoff.