LAKE TAHOE, Calif. -- Some horses and their riders will be put to the ultimate challenge in the Sierra this weekend in a race called the Tevis Cup.

Tevis is a 100-mile race across the Sierra on the notorious Western States Trail, which takes riders from Robie Park, near Lake Tahoe, to the fairgrounds in Auburn. The race is 100 miles of rough, hot and dusty trail that is completed within 24 hours.

"It's scary. It's really scary. It's overcoming your own terror and connecting with an animal," said rider Linda Upton.

"It's a blast. It's really a blast, very much fun," said rider Jenni Smith.

Riders start at 5:15 a.m. Saturday morning and have until 5:15 a.m. Sunday to finish. Many will use the entire 24 hours, and less than half who start the ordeal will finish, according to race officials. All of the contestants are after the coveted Tevis Cup belt buckle.

Seiichi Hasumi is back for his second ride. He first took on the grueling race last year at the age of 60. He finished 22nd in a field of a 150 riders, which is amazing considering he says he had never ridden a horse before.

Hasumi says he got the idea of racing in the event after seeing a documentary on Japanese TV.

"I suddenly want to participate in Tevis Cup. I want to be excited in the rest of my life," Hasumi said.

To learn more about the Western States Foundation and the Tevis Cup ride, CLICK HERE.