Usain Bolt breezes into 100 metres semi-finals at rapturous Olympic Stadium

Defending champion Usain Bolt strolled into the semi-finals of the 100 metres today as Olympic history was made on a lightning fast track in London.

Bolt stumbled out of the blocks in heat four but was soon into his running and looking around at his competitors, the Jamaican doing just enough to win in 10.09 seconds.

But that time looked positively pedestrian after first Justin Gatlin and then fellow American Ryan Bailey broke 10 seconds, a feat never before achieved in the heats of the Olympics.

Gatlin clocked 9.97secs in heat two, only for Bailey to then equal his personal best of 9.88 in the next heat to raise hopes that Bolt's world record of 9.58 could be under threat in tomorrow's semi-finals and final.

Bolt said: "I am feeling good, my legs are feeling good so I am happy. I am training well so I feel like I'm back. My start was good, I am only focused on the semi-finals tomorrow."

Former world champion Tyson Gay eased through in 10.08.

British sprinters Adam Gemili, James Dasaolu and Dwain Chambers all advanced to the semi-finals, with world junior champion Gemili, in 10.11, second behind former world record holder Asafa Powell in his heat.

Chambers, a beneficiary of the British Olympic Association's Games ban for past doping offenders being overturned, had not run quicker than 10.25 in 2012 until today when he clocked 10.02.

He said: "I don't know where 10.02 came from, I've been running 10.2 all summer, but I know that isn't me. I've just put it together at the right time, but I wasn't expecting to run that fast.

"It was difficult because my last Olympic experience was 12 years ago, and I still remember it clearly to this day. The main point is I have become eligible to compete here and I wanted to be sure I made my team, my friends, my family and my supporters proud."

Chambers will be in the lane next to Bolt in tomorrow's second semi-final, while Gemili will be alongside Blake in the third race, with only the first two in each of the three semis guaranteed to make the final.

Great Britain's Jessica Ennis stands just 800 metres away from Olympic heptathlon gold after she continued to dominate the competition.

Ennis opened up a 188-point lead over Lithuania's Austra Skujyte with Ukraine's Lyudmyla Yosypenko third, and tonight's two-lap race will decide who takes the medals.

Three men went under 45 seconds in round one of the 400m, with Jonathan Borlee quickest in a Belgian record of 44.43 seconds.

South Africa's Oscar Pistorius became the first double amputee to compete in the Olympics and Paralympics and the 'Blade Runner' made the semi-finals as defending champion LaShawn Merritt crashed out.

Pistorius was second in the opening heat to advance, while Merritt pulled up injured around 120m into heat six after failing to recover from a hamstring injury suffered in Monaco recently.

Merritt said: "You couldn't even imagine [what I've been through to get here]. Countless hours of treatment from 8am till about 10pm.

"I thought I could come out and get my way through but I'm still young and I have a long career ahead of me. There was no reason to push it. Once I got on that back stretch I started floating and I felt it."

Two-time Olympic champion Yelena Isinbayeva topped the list of qualifiers for the women's pole vault.

PA