Defending champion Usain Bolt strolled into the semi-finals of the 100 metres 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 for the first time in the heats of the Olympics.
Gatlin clocked 9.97secs in heat two, only for Bailey to then equal his personal best of 9.88s in the next heat to raise hopes that Bolt's world record of 9.58s could be under threat in tomorrow's semi-finals and final.
Bolt's oft-stated hopes of becoming a "legend" of the sport by defending his 100m and 200m titles had looked in doubt after he lost twice to compatriot Yohan Blake at the Jamaican trials and needed treatment on a stiff back which was causing hamstring problems.
The 25-year-old insisted last week he was fit and ready to compete against the likes of training partner and world 100m champion Blake, who eased to victory in 10.00 in his heat.
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."
British trio Adam Gemili, James Dasaolu and Dwain Chambers all advanced to the semi-finals, with world junior champion Gemili (10.11) second behind former world record holder Asafa Powell in his heat.
Dasaolu was third in Bolt's heat in a season's best of 10.13, while former drugs cheat Chambers - back in the Olympics for the first time since 2000 - won the final heat in a season's best of 10.02.
Gemili, 18, only concentrated fully on athletics in January this year but was the fastest man in Britain until Chambers' run in the final heat.
"I was nervous but I just wanted to try and focus and do a good race and execute it properly," he said. "When you walk out in front of a crowd like that it's amazing.
"Having Asafa in the heat was good, he's one of the best athletes of all time so to do quite well against him is good."
Speaking after racing in the lane next to Bolt, Dasaolu added: "He is the quickest guy in the world ever to live; it's just amazing, words can't describe how that felt.
"I think I had a good race, a decent start and I tried to roll along with Usain. He dragged me along from a qualification race into the semi-final, so I'm really pleased with that."
Chambers had not run quicker than 10.25s in 2012 until today - while former
world champion Tyson Gay eased through in 10.08 - and 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 final race with only the first two
in each of the three semis guaranteed to make the final.
Dasaolu is in the first semi with Powell and Gatlin.
