LONDON - China's swimming standouts Liu Zige and Jiao Liuyang, winner and runner-up of 200m butterfly at 2008 Beijing Games, cruised into the semifinal of their signature event at London Olympics on Tuesday.

Jiao, champion at the Shanghai world championships last year, finished as the second fastest qualifier in morning's heats.

Liu, who is the world record holder of 2:01.81, clocked 11th overall into evening's semifinal.

"I just kept my pace in the heats. I focused more on the 200m butterfly in my training as compared to the 100m," said Jiao, who will also swim the 100m butterfly in London.

"The 100m and 200m (butterfly) are different in terms of the technique. I didn't do very well in my 100m, but I hope I will keep going in the 200m," she added.

Jiao is tipped as a hot favorite for a medal, even the gold, in the final scheduled on Wednesday evening.

"I'm not that ambitious. I just want to follow my pace as I was trained. I don't want to push myself too much and give myself much pressure," she added.

Liu, bronze medalist in the 2011 Shanghai world championships, was not going allout in the heats.

"I was quite tired. I didn't feel in top form. But I hope I will perform well in the semifinal," she told reporters.

China had a remarkable start in the pool with Sun Yang and Ye Shiwen took two gold medals in men's 400m freestyle and women's 400m individual medley, respectively.

Ye, 16, is set out for another gold medal on Tuesday evening in the 200m individual medley, which she was crowned champion at the Shanghai world championships. She was the fastest qualifier with a new Olympic record.

Liu Zige of China competes in the women's 200m butterfly heats swimming event during the London 2012 Olympic Games at the Aquatics Center July 31, 2012. [Photo/Agencies]

Jiao Liuyang of China competes in the women's 200m butterfly heats swimming event during the London 2012 Olympic Games at the Aquatics Center July 31, 2012. [Photo/Agencies]