China all smiles but Miley is left in the wake

Two golds and a world record for hosts of the last Olympics sink hopes of an early British medal

It was an evening that opened to the sound of the 'Star-Spangled Banner' echoing around the London Aquatics Centre but it was a night that belonged to China, emphatically so. In less than half an hour two stunning swims produced two Chinese gold medals and already they have doubled the total they managed in home waters four years ago.

First Sun Yang, a swimming superstar in the making, claimed an utterly dominant victory in the 400m freestyle and then, minutes later, 16-year-old Ye Shiwen shattered the world record with an even more remarkable success in the 400m individual medley.

Ye left the American favourite Elizabeth Beisel trailing in her wake over the last 50 metres. The sheer strength of the Chinese swimmer shattered the field – Hannah Miley, carrying Britain's hope of a first home medal, could not compete and finished fifth, nearly six seconds adrift. The bronze went to China, too, through 18-year-old Li Xuanxu.

Ye had set the fastest time of the year in the morning heats amid a growing sense that China could become the story of the pool in London. Before last night they had a historic total of seven golds – they won six medals of all colours in 2008 – but theirs is a strident ambition to improve in sports beyond their traditional strengths and in the pool it is coming to fruition.

Yang destroyed the field in the 400m freestyle to claim the first gold medal China's men have ever won in the pool. The 20-year-old was under intense pressure to deliver in London; in the build-up to the Games his membership of the Communist Party was hurried through. He is the world record-holder at 1500m – breaking Grant Hackett's 10-year-old mark at last year's World Championships – and looks set to dominate the middle and long-distance events.

In Beijing before departing for London, Yang climbed on to a table at a team meeting and yelled: "We are coming – London, Chinese men are coming." His confidence was not misplaced, but his facts were wrong – the women are here too.

The 6ft 6in Yang eased away from Korea's Park Tae-hwan early on and the defending champion never looked like closing the gap. Yang finished in an Olympic record time having threatened to break another world record for much of the race.

That record was not long delayed. Ye, who took up swimming at the suggestion of a primary school teacher who noticed she had extremely large hands for her age, had finished fifth at last year's World Championships but has improved spectacularly since then in the most gruelling event in the pool. And the biggest worry for her rivals is that the 400m is not her specialist event – she is world champion in the 200m IM. There will be more Chinese medals to come.

Beisel had seemed to have the race under control but could not handle Ye's brutal acceleration over the final length. She touched in 4min 28.23sec, more than a second inside the record set by Stephanie Rice in Beijing.

Miley was never in contention. She started slowly and was sixth at the halfway stage. She used her strong breaststroke to regain some ground but, like the rest of field, could do nothing about Ye's power. The 22-year-old Scot, who was ranked third in the world going into the Games, broke down in tears. But it was Rice who summed it up best. A double Olympic gold medallist in Beijing, she came sixth last night. "Oh my god, it was so tough," she said.

Britain's Ellen Gandy qualified seventh fastest for tonight's final of the 100m butterfly. The Australian-based 20-year-old finished fifth in her heat behind the dominant Dana Vollmer of the USA. The 100m is Gandy's weaker event – she is a world silver medallist at the 200m fly – but she cut half a second off her morning time to reach a first Olympic final.

Fran Halsall failed to make the final. The 22-year-old faded over the second 50 metres to finish seventh in her semi-final. Halsall later produced a stirring second leg of the 4x100m relay to help Britain finish a creditable fifth. It bodes well for Halsall later in the week. Australia took the gold, the Dutch silver and the USA bronze to give Missy Franklin the first of a possible seven medals.