OMAHA -- Twelve past champions are scheduled to play in the U.S. Senior Open that will be held next month at Omaha Country Club. The U.S. Golf Association on Thursday announced 78 of the 156 spots have been filled. Remaining spots will be taken by golfers who advance in sectional qualifying later this month and by eligible winners of official PGA Tour and Champions Tour events in the weeks remaining before the Senior Open. Returning champions are 2012 winner Roger Chapman, Olin Browne (2011), Brad Bryant (2007), Allen Doyle (2005, 2006), Dave Eichelberger (1999), Fred Funk (2009), Hale Irwin (1998, 2000), Peter Jacobsen (2004), Bernhard Langer (2010), Graham Marsh (1997), Don Pooley (2002) and Eduardo Romero (2008). Other familiar names are Colin Montgomerie, Mark Calcavecchia, Fred Couples, Tom Kite, and Tom Watson.