China's first-ever Olympic eventing rider Alex Hua Tian did not expect to end his Games debut on the ground.

Unfortunately for the young rider, that is exactly what happened when a fall during the cross-country competition Monday morning at Beas River, Hong Kong, disqualified him from the competition.

"I am very disappointed with myself. It's completely my fault," the 18-year-old told China Daily over the phone after his disqualification. Eventing rules say any rider who falls off his horse during a match cannot continue to compete.

China's Alex Hua Tian rides Chico during the equestrian eventing cross country competition at the Beijing 2008 Olympic Games in Hong Kong August 11, 2008. [Agencies]

"I completely missed the stride. My horse (Chico) was perfect and I completely messed it up. I can't believe it has all ended with a fall."

His father Hua Shan thought the difficult cross-country course was the cause of Hua Tian's troubles.

"These obstacles are not very difficult to jump over but the course is very technical," Hua Shan said. "Alex just lost his rhythm between the jumps and then fell off the horse."

The course, which runs over a golf course, consists of 39 jumps and covers a distance of 4,560m (most courses measure 5,700m). Many riders identified the shorter course, with its hilly terrain and bending track, as a key challenge. The US, British and Australian teams all described the course as "technical", requiring the rider to plan carefully.

"This is a more technical course than Athens. The angles are tough and you have to present the horse on the right lines," said Amy Tyron, a US team bronze medalist at the 2004 Athens Games.

Hua Tian's Australian coach Clayton Fredericks, who is also competing in this Olympics with his wife Lucinda, pointed out that time management is crucial, as a rider must finish the course within about 11 minutes.

"There is no time to spare. You have to let the horse gallop and have confidence in him. If you break the stride for each obstacle, you won't make the time," he said.

Chinese Equestrian Association director Cheng Qing felt bad for Alex's performance and said his lack of match experience led to his disappointing performance.

"Many people had too much expectation for Alex before the match, but he is only an 18-year-old young man with few major events under his belt," he told China Daily.

"He tried to ride faster to make up time during the competition but lost his rhythm. Anyway, it will take time for him to gain experience."

Hua Tian, the youngest eventer in Olympic history, kicked off his performance on Saturday at the dressage competition in Sha Tin. He and Chico, his 12-year-old grey German breed, finished 31st among 70 participants with penalty points of 49.6.

It was the first time China participated in an Olympic equestrian event. The host was automatically allocated six berths - one in eventing, one in dressage and four in jumping.

"The other five Chinese riders are ready to go in Hong Kong. Their horses are fine too," the director said.