Phelps swims for record eighth gold at Olympics

Beijing: Michael Phelps swims for a record-breaking eighth gold in a single Games on Sunday to end a stunning week of achievement in the Olympic pool.

The American has hogged the headlines over the first week with his quest to beat Mark Spitz's record, but late on Saturday Jamaican Usain Bolt also etched his name into Olympic history by becoming the fastest man on earth.

Bolt set the Bird's Nest stadium alight with his 9.69 seconds burst to cruise to Olympic gold in the 100 metres, in the process smashing his own world record. Phelps will dive into the Water Cube pool not long after the women marathon runners cross the Bird's Nest stadium finish line following an early Sunday morning start to ward off summer heat.

A warm, sunny day is forecast for the 42 km race that starts in Tiananmen Square, in the heart of the Chinese capital, though the suffocating humidity and smoggy haze of the early days of the Games have been replaced by blue skies.

Phelps has already equalled Spitz's 1972 record of winning seven golds in one Games and become the most successful Olympian of the modern era with a career tally of 13 wins.

He will stand alone in the record books if he and his team mates win the men's 100 metres medley on Sunday morning.

A second-string US squad qualified fastest in the heats, setting their "A-team" colleagues up as firm favourites.

Phelps will be glad to avoid further nail-biting moments after winning his seventh medal on Saturday by a fingertip. "One hundredth is the smallest of margins of victory in sport.

It's pretty cool, that's all I can say," he said. Saturday's gold earned him a $1 million bonus from his swimsuit sponsors, but that will be dwarfed by the corporate endorsements he will garner if he surpasses Spitz's record. Spitz has hailed Phelps as the greatest Olympian ever and his achievement as epic.

The men's relay concludes a week of record-breaking performances in the pool. Attention will then switch firmly to athletics, where Bolt's sprint on Saturday night showed that the track too might provide a happy hunting ground for record seekers.

Flag raisers will be at their busiest on Sunday, with 37 golds to be awarded, the most of any day of the Olympics.

Athletics sees six golds decided, including the women's 100m sprint and the men's 10,000m, rowers will compete for seven golds, tennis finals conclude and the becalmed sailors hope the wind will pick up to let them finish some competitions.

Australia's Grant Hackett hopes to become the first male swimmer to win the same Olympic event three times.

The world record holder qualified fastest for the 1,500 freestyle. Kenyan world champion Catherine Ndereba starts the marathon as favourite, with the 36-year-old mother saying she is used to running in warm conditions.

World record holder Paula Radcliffe was memorably defeated by the heat and illness in the Athens marathon in 2004. She has struggled to recover from a stress fracture in her leg that made her participation in the race doubtful.

China's Zhou Chunxiu, winner of the London marathon last year, will be cheered on vigorously by the home crowd and will be used to Beijing's sweltering weather, as will compatriot Zhu Xiaolin. The race starts at 0730 hrs (local time) (2330 GMT) and heads in a 10 km loop around central Beijing before heading north to the Olympic stadium on a relatively flat course.