Justin Gatlin of the US cemented his status as the world's fastest man when he claimed the 100 metres gold medal with the widest victory margin in event history at the World athletics championships here Sunday.

Gatlin, 23, ran away from all rivals in the second half of the race to win in a personal season-best 9.88 seconds, with Jamaican Michael Carter a surprise second and title holder Kim Collins of the Caribbean island of St. Kitts and Nevis third. Both were timed on 10.15 seconds.

The margin of 0.17 seconds was bigger than Carl Lewis' victory by 0.15 seconds over Jamaican Ray Stewart 1987 in Rome (9.93 to 10.08 seconds).

"I ran like a champion. It is a great consolation to show how dominant I am. I am the Olympic champion and the world champion, but I want Justin Gatlin to be the champion of everything," said Gatlin, who won Olympic gold last year in Athens.

While Gatlin won easily, Carolina Kluft of Sweden needed to give it all she had to prevail over French Eunice Barber in an epic heptathlon battle she finally won by 63 points for back-to-back world titles.

Earlier, Olimpiada Ivanova of Russia won the 20km walk in world-record time, Virgilijus Alekna of Lithuania retained his discus title on the final attempt of the competition and Trecia Smith gave Jamaica a women's triple jump gold.

The Helsinki evening sky was painted blue and pink for the blue-riband 100m race, which quickly became a one-man show, so dominant was Gatlin in the Olympic stadium filled almost to its 40,000 capacity.

"I didn't have the greatest start, but then I pulled away. I yelled out loud halfway through the race because I knew I had it," said Gatlin.

Frater cried tears of joy in the arms of team-mate and training partner Asafa Powell after saving Jamaican pride with a surprise silver, with Collins showing his class in big events and naming the bronze "as good as the gold two years ago".

Powell, the world-record holder with 9.77 in June, was sidelined with a groin injury and said he will also not compete in the relay before meeting Gatlin on Aug 19 in Zurich.

A showdown did take place in the heptathlon, where the Olympic champion Kluft fought through an ankle injury, headwind and a 152-point deficit on Barber after two events to gold with a personal season-best 6,887 points.

Barber had to settle for silver like in 2003 with 6,824 points. Bronze went to Margaret Simpson of Ghana with 6,375 points.

"This was the most difficult competition of my career due to the injury. I knew I had to reach the finish line before Eunice to get the gold, and that's what I did," said Kluft.

Ivanova raised the walk world record by 41 seconds to 1:25:41 to win the women's 20-kilometres walk for the second time following 2001. Ryta Turava of Belarus took silver in 1:27:05, and the bronze went to Susana Feitor of Portugal in 1:28:44.

"This victory makes me the happiest person here. I found my pace after the first few kilometres and felt fine," said Ivanova, who received a $100,000 world record bonus on top of $60,000 for first place.

Olympic champion Alekna threw a massive championships record 70.17 metres in his final attempt to steal the gold from Estonian Gerd Kanter, who had 68.57m for silver. German Michael Moellenbeck had 65.95m for bronze, as in 2001.

In the injury-related absence of two-time champ Tatyana Lebedeva of Russia, Smith soared a national record 15.11 metres for her first major triple jump title. Yargelis Savigne of Cuba got silver with 14.82m, and bronze went to Anna Pyatykh of Russia with 14.78m.

1998 European champion Christine Arron of France led the way with 11.03 seconds into the women's 100m semis, while three-time 800m champion Maria Mutola of Mozambique and the 2001 and 2003 400m hurdles champ Felix Sanchez of the Dominican Republic had lucky escapes into their finals.