Shawn Crawford denied fellow-American Justin Gatlin a sprint double as he set up a United States clean sweep in the Olympic men's 200 metres on Thursday.

The race, though, was marred by ugly scenes and delayed for five minutes when the packed 75,000 crowd at the Olympic Stadium began booing and chanting "Kenteris, Kenteris!" and "Hellas, Hellas!"

Costas Kenteris, Greece's 2000 Olympic champion in the event, withdrew from the Games after missing a drugs test in mysterious circumstances the day before the opening ceremony. There was no Greek runner in Thursday's race.

Crawford timed 19.79 seconds. Silver went to Bernard Williams (20.01) with Justin Gatlin, the 100m winner, taking the bronze (20.03).

It was the first American clean sweep in the event since 1984.

The crowd spared only one man with their jeers before the start, cheering wildly when former 200 world champion Frank Fredericks, set to retire after Athens, was introduced.

The Namibian began pleading with them to be quiet as the protest continued. Fredericks finished his top-level career with fourth place.

The 26-year-old Crawford, who just missed out with fourth in the 100, was in control on the crown of the bend in his specialist event before winning comfortably.

The 100, he had said, was just a "relax race" for him. In the 200, however, he meant business.

Before Thursday, Crawford had a reputation for being more clown than the showman he aspires to be.

Once he raced a zebra and a giraffe on American television, beating the latter but outsprinted by the former. He demanded a rematch, accusing the zebra of a false start.

Then there was the time two years ago when he wore a 'Phantom of the Opera' mask in a race in Italy. The mask slipped, Crawford ran out of his lane and was disqualified.