Karen O'Connor and Mandiba have taken the first-day lead at the Rolex Kentucky CCI**** Three-Day Event, presented by Bridgestone, scoring 43.7 penalties.

Becky Holder rode Courageous Comet to second place (45.2), and Phillip Dutton rode The Foreman to third place (47.2).

O'Connor, 52, won the Rolex Kentucky Three-Day Event in 1999, while Dutton, 46, won the 2008 event. All three of the leaders are also Olympic veterans and are among the leading candidates for the U.S. team that will compete at the 2010 Alltech FEI World Equestrian Games.

O'Connor, of Middleburg, Va., said that Mandiba's performance today was consistent with his other performances so far this year. "He's more confirmed than he's ever been, for sure, so I can ride down the centerline with more confidence than ever before," said O'Connor