American Justin Gatlin has run the four fastest 100m times this year, setting a personal best of 9.74 in May.
But Bolt twice ran under 10 seconds at the Olympic Stadium on Friday to show he is coming back to form after injury.
“I was never number two, I am still number one. Until I retire that’s the plan,” said the double world champion.
“I’m ready to go and I’m ready to win.”
“I don’t fear anyone,” he told BBC Radio 5 live sport.
“It’s all about hard work and dedication and pushing myself.”
The pelvic problem which forced him to withdraw from Diamond League meetings in Paris and Lausanne this month did not hinder him as he ran twice in 80 minutes on the first of a two-day Diamond League meeting in London.
“Anything is possible in Beijing – it’s all about the effort you put in,” he added. “I’ve been running fast in training, but it’s easier in training because you’re under no pressure and you can execute well.”
By Aimee Lewis BBC Sport at Queen Elizabeth Olympic Park