US swimming sensation Michael Phelps beat his own world record in the 400m individual medley as he won his first gold medal of the Athens Olympics.
Phelps, 19, who was going for a record eight gold medals at the Games, never looked in danger of finishing second.
The American won in four minutes 08.26 seconds, 0.15 seconds faster than the mark he set at July's US trials.
Phelps' American team-mate Erik Vendt took the silver medal and Hungary's Laszlo Cseh won the bronze.
Vendt - a silver medallist at Sydney in 2000 - finished in 4:11.81, more than three-and-a-half seconds behind Phelps, with Cseh clocking 4:12.15.
"This is a dream come true. Ever since I was a little kid every day I woke up hoping to win Olympic gold," said Phelps after the race.
"And it means more with Erik finishing second. I heard him scream and looked at the scoreboard and I just went nuts. I flipped out."
He added: "I had tears after the race and I can feel tears coming again."
Phelps' first final, as he goes for his eight medals, is among his stronger events, with the teenager nearly four seconds faster than anyone else in the world this year coming into Athens.
Phelps cruised into the final with a time of 4:13.29 in the morning preliminaries.
He went much faster in the final, building a full body-length lead by the time the eight swimmers went down and back on the butterfly.
The win marked the fifth time that Phelps
has broken the world record for the 400m individual medley.