Hicham El Guerrouj stamped his authority on the final day of the eighth world championships on Sunday with a third consecutive 1,500 metres title.
He then announced he would move up to the 5,000 in an acknowledgement that he would not now win the Olympic title over the distance he has dominated for the past five years.
"I wanted to have the best race of my life because that was my last 1,500," said El Guerrouj, who clocked three minutes 30.68 seconds ahead of Kenyan Bernard Lagat. "It's fantastic. It's unbelievable".
Two other great champions graced the final day of the championships.
Olympic champion Maria de Lourdes Mutola of Mozambique regained the world 800 metres title after a desperate lunge for the line ahead of close Austrian rival Stephanie Graf.
Mutola won in one minute 57.17, three-hundredths of a second ahead of Graf in the closest finish to a world championships women's 800 metres final.
Czech Jan Zelezny confirmed he is the greatest javelin thrower ever with a third world title to add to his three Olympic gold medals.
Now 35, Zelezny won with a second-round effort of 92.80 metres, a personal best at a world championships.