Jeremy Wariner stepped into Michael Johnson's shoes and led a US sweep in the 400 metres, powering down the stretch to edge Otis Harris for his first major title.

Wariner clocked 44 seconds, his personal best and fastest in the world this year, to stretch the Americans' winning streak in the event to 20 years and pick up where the retired two-time champion Johnson left off.

Harris won the silver in 44.16, and Derrick Brew took the bronze in 44.42.

It was the first US sweep of the medals in the 400 since the 1968 Mexico City Olympics.

"It means a lot. We all thought we could go out there and go 1-2-3. We did our best, we fought hard, and we all came out on top," Wariner said, showing no sign of emotion. "It hasn't sunk in yet."

Wariner has Johnson's old coach, Clyde Hart.

Kelly Holmes took away her friend Maria Mutola's 800-metre Olympic title in a close race that saw the defending champion shut out of the medals.

Francoise Mbango Etone gave Cameroon its first Olympic medal in athletics when she won the triple jump at 15.30 metres.

"I was very proud to get the medal and set the African record," she said. "I want to dedicate this medal to the whole of Africa."

Meseret Defar of Ethiopia pulled away with 200 metres left to win the 5,000 in 14:45.65. Isabella Ochichi of Kenya took the silver in 14:48.19 and another Ethiopian, world champion Tirunesh Dibaba, won the bronze in 14:51.83.

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