By Alison Wildey

LONDON (Reuters) - Decathlon world record holder Ashton Eaton got his Olympic challenge off to a flying start to hold a lead of 105 points over U.S. team mate Trey Hardee at the top of the leaderboard after three events on Wednesday.

Eaton, who set the world mark of 9,039 in June, opened with the fastest 100 meters in an Olympic decathlon of 10.35 seconds.

The American then won the long jump with 8.03 meters before going close to his personal best in the shot put with 14.66.

"I feel good my body feels good," Eaton told reporters. There was nothing special but they were all solid which is what it takes to get good scores in the decathlon."

Eaton has 2,848 points with world champion Hardee second on 2,743 and Ukraine's Oleksiy Kasyanov in third (2,664).

"How sweet is it to look at leaderboard and see a U.S. one-two," Hardee said.

"I think we all envisioned that. It should stay that way the rest of the time. But it doesn't mean anything now... it's all leading into that 10th event and what it looks like when you cross the line."

The high jump and 400 meters take place later on Wednesday with the remaining five events in the decathlon on Thursday.

(Additional reporting by Gene Cherry, Editing by Nigel Hunt)