Of all the sights to see during the nine-day Capital Challenge Horse Show at the Prince George's Equestrian Center in Upper Marlboro, perhaps the most surprising was Kim Frey falling off her horse Saturday night -- following her victory in the Congressional Cup Grand Prix.

After all, Frey twice that night had flawlessly raced her chestnut mare, Marlou, through a half-minute routine that involved leaping over 14 wooden-beam obstacles, some of which were the size of small pickup trucks.

She finished in 32.73 seconds, 0.07 second faster than runner-up Lauren Bass and 32 other entrants.

But as the blue ribbon-festooned Marlou led the other finishers in a victory gallop before retiring for the night, the 10-year-old Dutch Warmblood suddenly stumbled and dislodged Frey, who fell to her feet onto the sandy floor.

"My horse gets very excited in victory gallops," said Frey, of Hume, Va. "Sometimes she is very out of control following the other horses because she bucks. But as Margie Engle once told my 6-year-old daughter [Lydia], 'You are not a rider until you fall off.' "

Engle, who competed at the 2000 Sydney Olympics, was one of 12 former Olympic riders in Saturday night's competition, the highlight of the Oct. 2-10 event. Another participant was Georgina Bloomberg, the daughter of New York Mayor Michael Bloomberg.

The Grand Prix draws top competition with prize money and the chance to earn qualifying points for the annual World Cup jumping competition, held next spring in Las Vegas. The Washington International Horse Show, which will take place this month at MCI Center, is the only other indoor competition in the Washington area that counts as a World Cup qualifying event.

On Saturday night, Frey was one of eight riders who advanced to a jump-off round, and she eventually won $12,000 of the $40,000 purse by completing the course in the fastest time without knocking down a beam.

"It's a really nice showing here, and the people come and it's a really nice crowd and they enjoy watching the horses," Frey said. "I think you get a lot of people who love horses from the Maryland and Virginia areas."

Scenes from Saturday's Congressional Cup Grand Prix event at Prince George's Equestrian Center. Clockwise, from top: Lauren Hough takes Casadora over a jump; McLain Ward, an Olympic silver medalist, takes Quickstar II Z over a jump; and Todd Minikus rides Gardenio, left, off the arena as Kim Frey readies to take Marlou onto it. Frey and Marlou won the event.