Ye Shiwen returned to the Olympic pool after her super-fast 400m Individual Medley swim to easily head the field in the heats of the shorter medley event.

Ye Shiwen of China speeds through heat 5 of the women's 200m Individual Medley on Day 3.

The 16-year-old produced a mind-boggling final 50m freestyle on Sunday that was quicker than Ryan Lochte, the winner of the men's equivalent.

It saw her cut more than a second off Stephanie Rice's 2008 record and the Chinese swimmer's effort has caused a sensation.

She was easily quickest today in the women's 200m Individual Medley, in which she is world champion. Her time of 2:08.90 was 1.61 ahead of Kirsty Coventry.

Defending champion Rice, who qualified ninth, said: "I really just wanted to get into the semis. I knew I was against Ye Shiwen. She's a great 400 swimmer, she comes home like a gun in that Freestyle."

Of Ye's 400 Individual Medley, the Australian said: "Insane. I mean I didn't see it, I was way over and behind, so I didn't really see her coming home, but that split coming home was out of control, faster than everyone but (Michael) Phelps I think."

"So if I was up with her I would have had no chance anyways."

Defending champion Federica Pellegrini was quickest through in the women's 200m Freestyle heats in 1:57.16.

Dinko Jukic qualified fastest in the men's 200m Butterfly heats in 1:54.79, with Phelps back in fifth.