Bolt ready to fire in 100m defence

Jamaican sprint legend Usain Bolt labelled himself the underdog as he seeks to round off his glittering individual track career with the defence of his world 100m title this week.

"That's what I keep reading and what my team keeps telling me, so I've got to prove myself again," the 30-year-old said in a warning shot to pretenders to his crown in the blue riband event of the IAAF World Championships.

Bolt started this season in sluggish form, running two 10sec-plus times before finally hitting some form at the Monaco Diamond League.

"The last race I ran was 9.95sec, which shows I'm going in the right direction," he said.

"It's a championships and the two rounds always help me. I've been here many times. It's go-time, so let's go!"

He added: "Usain Bolt has retired unbeaten in an individual event, unbeatable, unstoppable -- for me that would be the best headline!

"If I show up at a championships you know I'm fully confident and ready to go, and my coach, I'm ready to go."

Bolt refused to single out who would be his closest rival for the 100m, with heats on Friday before the semifinal and final on Saturday at the same stadium in east London where he won treble gold at the 2012 Olympics.

"The seven people who are going to be in that race with me, they're the biggest challengers," he said.

Bolt has dominated sprinting since taking double individual gold at the Beijing Olympics in 2008, going on to win a further six Olympic golds and also picking up 11 world titles.

He also holds world records of 9.58 and 19.19sec in the 100 and 200m, both set when winning at the 2009 Berlin worlds.

In a glitzy press conference organised by his long-term sponsors Puma and hosted by Welsh ex-hurdler Colin Jackson, Bolt picked out his then-world record breaking victory in the 200m at the Beijing Olympics in 2008 as the stand-out performance of his career.