US swimmer Michael Phelps stayed on course for an unprecedented eight gold medals, winning the men's 400m individual medley in world record time on Sunday, the dpa reported.
Watched by US President George W Bush, Phelps won his seventh Olympic gold overall, breaking his 23rd world record in a time of 4 minutes 3.84 seconds.
He announced afterwards that he would no longer swim the 400 individual medley.
Another world record fell in the women's 400m individual medley with Australian Stephanie Rice taking nearly two seconds off the world best.
Rice clocked 4 minutes 29.45 seconds for her first major title and Kirsty Coventry of Zimbabwe was also below the previous record with 4:29.89 for silver.
Favourite Katie Hoff had to settle for bronze in 4:31.71 and also lost the world record of 4:31.12 she swam on June 29 at the US trials.
But US-Australian domination in the Water Cube was interrupted by South Korean teenager Park Taeh Wan who won the men's 400m freestyle, thereby becoming the first South Korean to win a swimming gold medal.
In shooting, Guo Wenjun won China's second gold in the event with an Olympic record score of 492.3 in the women's 10 metre air pistol, salvaging Chinese pride after world record holder Ren Jie failed to make the final.
Natalia Paderina of Russia and Nino Salukvadze of Georgia took silver and bronze respectively and in what will become one of the enduring images of these games embraced for the cameras just two days after hostilities between their two nations erupted in the Caucasus region.
The gesture came after both Russia and Georgia said earlier Sunday that they will continue to compete in Beijing despite the hostilities, which started on Friday.
Away from the competitive action Chinese officials sought to reassure foreign visitors that they were safe in Beijing after the stabbing to death of the father-in-law of a US Olympic volleyball coach on Saturday.
The attack in Beijing in which the man's wife and a Chinese tour guide were injured, was an "isolated criminal act" and not linked to the Olympics, said Wang Wei, the executive vice-president of the Beijing Olympic organizers.
And doping-tainted Greek sprinter Katerina Thanou was told she will not be allowed to compete at the Beijing Games.
Thanou brought the Olympic movement into disrepute in a "a scandalous saga" four years ago, the International Olympic Committee announced on Sunday.
The world governing athletics body IAAF, which banned Thanou and fellow-sprinter Kostas Kenteris for two years over missed tests in 2004, did not complain about the IOC ruling.
"We respect this decision. We are not disappointed," IAAF spokesman Nick Davies told Deutsche Presse-Agentur.
Thanou, a 100m silver medallist from 2000, and Kenteris, the 200m Olympic champion in 2000, caused a huge scandal in Athens when they ran away from drug testers in the Olympic village on the eve of the opening ceremony.
They staged a motorcycle accident later that night and were hospitalised for several days. They then withdrew from the Games which prevented the IOC from continuing its investigation.