The world's top three sprinters, Usain Bolt, Asafa Powell and Tyson Gay, all eased into the Olympic 100 metres semi-finals today.

But Tyrone Edgar was the only one of three Britons to make it beyond the second round.

In the first, Simeon Williamson, 22, was punished for being slowest out of the blocks as he finished fourth in 10.32sec.

World champion Gay looked comfortable as he came second in the second heat in 10.09 behind the Trinidad sprinter Richard Thompson.

It was only Gay's second race since injuring his hamstring at the US trials in early July. Edgar then booked his semi-final place by ducking at the tape to come third in the third heat in 10.10 secs.

Bolt won his heat in consummate ease in 9.92 - the fastest 100m run in China - but Craig Pickering crashed out two lanes away from the world record holder as he managed only fifth place.

Jamaican Powell, the former world record holder who is the second fastest man in history, eased off towards the end of his heat as he crossed the finish line in 10.02.

Both the semis and the final - arguably the most eagerly anticipated in recent Games - takes place in the Bird's Nest stadium tomorrow.