Swimmer Michael Phelps demolished his own world record to take a first gold on Sunday in the quest for an unprecedented eight wins, but violence in the far west again marred the Beijing Olympics party. 

Listening to hip-hop on headphones as he walked to the block, Phelps went on to win the 400 metres individual medley at China's futuristic and full-to-capacity Water Cube. His time was 1.41 seconds quicker than a previous best he set just six weeks ago.

After the first race of a thrilling morning at the pool, Phelps raised his arms to celebrate triumph in what he calls his weakest event.

He was watched by President George Bush and cheered by flag-waving compatriots and thousands of Chinese.

"I'm pretty happy with that ... it was all adrenaline," said Phelps, describing Bush's presence as "pretty cool."    

Even if the lanky 23-year-old with the perfect swimming physique wins only half his eight race competitions, he will hold more Olympic gold medals than any other athlete. But he looks in great shape to match his own six golds at Athens 2004 then maybe go one further than Mark Spitz's 1972 record of seven wins at one Games.

Despite the Phelps phenomenon, the Games' Day Two was spoiled by pre-dawn blasts and a shootout in Xinjiang, some 3,000 km (1,860 miles) west of Beijing.
State media said "lawbreakers" tossed homemade explosives into local government buildings. Five attackers were shot dead by police, and two officers plus a security guard injured.
Suspected Muslim militants killed 16 police in the same region a week ago.
   

It was not known who was behind Sunday's attack.

Beijing says it has foiled past plots to sabotage the Olympics by separatists in Xinjiang. Critics accuse China of exaggerating the threat to justify repression of dissidents.

Chinese authorities hope the Games will finally put the spotlight on sports after a build-up dominated by accusations of rights abuses and concerns over pollution despite Beijing's desire to showcase its modern face and economic might.

On the first day, though, a Chinese man stabbed to death the father-in-law of a US men's volleyball coach at a tourist spot.
Beyond China too, distant crises spoiled the Games' intended spirit of international harmony.

Georgia's team offered to withdraw over the conflict with Russia in South Ossetia. But President Mikheil Saakashvili sent a message overnight instructing them to stay.

"(She) told us we should stay in the best interest of the country," team spokesman Giorgi Tchanishvili told Reuters of a message read to athletes by Georgia's First Lady at 2 am.

After Phelps thrilled the Water Cube, Australia's Stephanie Rice followed suit to smash the world record and win the same 400m individual medley event for women.

Park Tae-hwan won the men's 400m freestyle to give South Korea a second gold while Zhang Lin became the first Chinese man to win an Olympic swimming medal when he grabbed the silver.

The Netherlands took an unexpected gold in the women's swimming 4x100m freestyle relay.
China came second in the medal table in Athens but aspire to outstrip the United States this time.

With 14 golds being awarded on Sunday, the hosts were well-placed to add to their first-day tally of two, with favourites in shooting, fencing, judo and diving.

Chinese diving queen Guo Jingjing, the supermodel of the springboard, steps up to defend her 3-metre synchronised title.

China dominates world diving and has a reasonable chance of winning all eight golds in the discipline.
Chinese fans are also focused on Sunday's basketball blockbuster between the hosts, led by 7ft 6in NBA player Yao Ming, against a star-studded United States still smarting from their bronze in Athens 2004.

It could be the most-viewed sporting contest ever in China.

Women cycl