American Bryan Clay outclassed the opposition to win gold in the Olympic decathlon on Friday, leading from start to finish in the two-day competition.

His winning margin of 240 points was the most convincing in the multi-disciplined event since 1972.

Clay, who was born in Texas, grew up in Honolulu and has both African-American and Japanese-American parentage, had victory in his pocket after building a huge 479-point lead going into the 10th and final discipline.

• Jamaica smash men's 4x100m mark

The 28-year-old could even afford to jog around the 1,500 meters as the scrap for silver and bronze took place well in front of him.

"I'm going home and getting something to eat and then straight to bed," Clay, who finished with 8,791 points, told reporters. "I've been telling people I'm in the best shape of my life, I've been training unbelievably hard."

Andrei Krauchanka of Belarus sealed the silver medal with 8,551 points after his best 1,500m time of the season. Cuban 20-year-old Leonel Suarez, who shone in javelin, overtook weary Russian Alexander Pogorelov to snatch bronze with 8,527.

With reigning Olympic and world champion Roman Sebrle out of form, Clay arrived in Beijing [Images] as favorite to add the Olympic gold to the world title he won in 2005.

Right from the 100m which started the event on Thursday, Clay, silver medalist in Athens four years ago, looked unbeatable. His only blip came in Thursday's high jump and 400m when the field closed to within 88 points.

CLASSY RUN

However, the American produced a classy run in the 110m hurdles at the start of the second day and never faltered again.

He posted a 53.79 meter discus throw to stretch his lead to 283 points before coming third in the pole vault and then launching the javelin to 70.97m for another big points haul.

Clay's American team mate Trey Hardee blew his chances of a medal when he failed to record a height in the pole vault. He had been third going into the second day.

The US had been on the podium in the previous two Olympics [Images] but Clay's victory was their first gold in the event since Dan O'Brien in 1996.

"I still look back in the book and see all the guys I look up to, I still go back in the books and look at all the things that they accomplished," Clay said.

"This is a start, and if my body holds up I will continue to 2012 and try and get another medal. I don't think many get decathlon medals at three Olympics."