American Justin Gatlin shot to victory in the Olympic 100 metres final on Sunday in an atmosphere of fevered excitement.
"I've been dreaming about this since I started racing," said an elated Gatlin after completing a victory lap of the Olympic stadium with a laurel wreath on his head.
"I've lived for this moment. It was a very great race, the competition was stellar."
The pre-race atmosphere resembled the build-up to a classic heavyweight title fight with the eight finalists waving and gesturing to the capacity crowd who had been clapping rhythmically to the theme tune from "Zorba the Greek".
Gatlin, 22, was slowest out of the blocks but powered back into contention, lunging over the line just ahead of Nigerian-born Obikwelu.
Greene, seeking to become only the second man to retain the Olympic title after Carl Lewis, was gracious in defeat. "I hope they (the fans) enjoyed the show we put on today. It was a great race."
At the other end of the scale, world silver medallist Mizuki Noguchi conquered the demanding marathon course from the town which gave the 42.195-km event its name to the Panathinaiko marble amphitheatre in the centre of Athens where the modern Olympic Games were revived in 1896.
Noguchi moved ahead in the second half of the race on a series of taxing inclines to win in two hours 26 minutes 20 seconds.
Kenyan Catherine Ndereba of Kenya took the silver with the bronze going to American Deena Kastor.
World record holder Paula Radcliffe of Britain laboured in the fierce heat and came to a sudden standstill after 36 kms, sitting down beside the road in tears.
It was another good day for the Swedes, following Caroline Kluft's win in the heptathlon on Sunday.
Christian Olsson added the Olympic triple jump gold medal to the world title he won in Paris last year and Stefan Holm took the high jump title when he was the only competitor to clear 2.36 metres.
Holm faced elimination after he failed twice at 2.34 but soared over the bar with his final attempt and cleared the winning height with his next jump.
Adrian Annus won Hungary's fifth men's hammer title in the other gold medal decided on Sunday.
Result: Men's 100m - Final
1. Justin Gatlin (USA) 9.85s
2. Francis Obikwelu (Por) 9.86s
3. Maurice Greene (USA) 9.87s
4. Shawn Crawford (USA) 9.89s
5. Asafa Powell (Jam) 9.94s
6. Kim Collins (Skn) 10.00s
7. Obadele Thompson (Bar) 10.10s
Aziz Zakari (Gha) Did not finish