Justin Gatlin of the United States became the fastest man in the world after winning the men's 100 meters dash at the 28th Olympic Games Sunday.

Gatlin, 22, clocked a personal best of 9.85 seconds for the gold medal, Portugal's Francis Obikwelu took the silver in 9.86 and defending champion Maurice Greene won the bronze in 9.87, his best of the season.

"It means the world to me. It's a dream come true, that's why I came here, to win the Olympic gold medal," said a jubilant Gatlin.

Gatlin knew that the gold was his after crossing the line.

"I had a great start and I had the ability to hold on from there. When I crossed the line, I knew for sure I was the winner.

"It was a close race, but I felt that I was a hundred miles from everybody."

Gatlin's sights has already set on the other two events and next year's world championships in Helsinki, Finland.

"I hope to extend this win to the world championships next year, but also to win the 200 meters. In fact I came here for three golds."

Obikwelu was satisfied with his silver medal and said he deserved that.

"I was not surprised. I knew I was ready. Yesterday I was very tired, I had two bad nights of sleep, but after the semifinal and a session with my physiotherapist and was really ready."

Greene, who dominated the race from 1997 to 2001, was happy with a medal.

"I expected a very close race between seven people, as I knew the ability of the others. I came a long way to come back and compete at this level. The final is everybody's race, so I'm pleased that I secured a medal."

Gatlin's win was a surprise since he had not had an impressive time in the qualifying rounds. He reached the finals by clocking a mere 10.09 seconds, second in heat 1 behind fellow American and training partner Shawn Crawford.

Crawford, who came to the Olympics with the world's season best time of 9.88 seconds, finished fourth in 9.89 seconds.

Gatlin's best performance before the Games was his 60m vicotry in the world indoor championships last year.

Gatlin made the US Olympic squad in July when he came second in both the 100m and 200m in the national trials.

Gatlin moved to coach Trevor Graham's training camp in 2002. Graham was also coach of women's sprinter Marion Jones, who won three gold medals in the Sydney Olympics four years ago but has been hit by doping allegations. Jamaica's Asafa Powell finished fifth in 9.94 seconds and reigning world champion Kim Collins of St. Kitts and Nevis sixth in 10.00. Barhamas' Obadele Thompson was seventh in 10.10 and the last entry Aziz Zakari of Ghana did not finish the race.

Olympic 100m results

1. Justin Gatlin (US)9.85

2. Francis Obikwelu (Portugal)9.86

3. Maurice Greene (US) 9.87

4. Shawn Crawford (US) 9.89

5. Asafa Powell (Jamaica) 9.94

6. Kim Collins (St Kitts-Nevis) 10.00

7. Obadele Thompson (Barbados) 10.10