Phelps joins elite Olympians with nine golds
Phelps put on an imperious display to capture his third medal of the Beijing Games, leading from the start to win in a new world record time of 1.42.96, knocking nine tenths of a second off his old record, a huge margin.
The American's third gold in Beijing, not even half way through his long march towards a target of eight, sets him beside US athletics great Carl Lewis, US swimmer Mark Spitz and Finnish distance runner Paavo Nurmi in the record books.
The lanky 23-year-old also has Spitz's record of seven golds at a single Games in his sights.
His exploits have helped draw huge audiences for the Olympics back home, where broadcaster NBC said they had more viewers for any summer Games held outside the United States since 1976.
One woman, Soviet gymnast Larysa Latynina, also has won nine Olympic golds.
Each of Phelps's victories in the Chinese capital have come in world record time.
In the women's races, Kirsty Coventry is aiming to bring some rare cheer to troubled Zimbabwe when she competes in the women's 100 backstroke final.
Silver medallist in Sunday's 400 individual medley, the US-based swimmer is in pole position after setting a world record in the semi-finals.
Australian world champion Leisel Jones, two individual silvers and bronze to her name from 2000 and 2004, is overwhelming favourite to snare an elusive individual Olympic gold in the 100 breaststroke final.
Aaron Peirsol, double Olympic backstroke champion in 2004, will have his work cut out in the men's 100 backstroke final after Australia's Hayden Stoeckl and fellow American Matt Grevers set the pace in the semi-finals.
PLEASANTLY COOL
Temperatures have fallen in Beijing to a comfortable 22 degrees Celsius (72 Fahrenheit) from the oppressive mid 30s at the weekend and the air has cleared, making life easier for outdoor athletes like rowers and tennis players.
New world number one Jelena Jankovic and the Williams sisters are safely through to the second round in the women's tennis, along with favourites Roger Federer and Rafael Nadal in the men's singles.
China are setting the pace at the top of the medals table with nine golds and may extend their lead on Tuesday, although the United States should hit their stride once the athletics gets underway at the end of the week.
The hosts hope for a clean sweep in the diving competition where they have picked up the first two golds on offer. Chen Ruolin and Wang Xin aim to make it three out of three in the women's synchronised 10m platform on Tuesday.
China are also fancied to pick up a couple more golds in weightlifting, and are overwhelming favourites for men's team gold in artistic gymnastics.
With memories of a 2004 Athens Games judging scandal lingering, the judges kept several of the Chinese gymnasts waiting for up to 10 minutes each as they tried to agree on scores during Saturday's qualifying round.
But the favourites still ended on top, ahead of 2004 champions Japan and former powerhouse Russia.
The Chinese team said they had taken their inspiration from "Prince of Gymnastics" Li Ning, who lit the cauldron at the opening ceremony on Friday, circling high above the heads of spectators in a daredevil high-wire act.
"The feeling it gave us was an older brother who was lighting the flame," gymnast Zou Kai told reporters. "It was very exciting and moreover it was on our home soil."