Sprint supremo Usain Bolt says he is taking his time in the build-up to August's 2015 World Championships In Athletics in Beijing and is looking forward to an explosive showdown there against American Justin Gatlin.

Bolt said he is ramping up, coming off an injury plagued season, but should be in high gear for the championships and ready to silence the confident Gatlin.

"I find a lot of stuff that he says really funny because I think he's trying to get a reaction out of me," Bolt told Reuters in an interview on 11 June ahead of Saturday's Adidas Grand Prix on New York's Randall's Island.

"For me, it's whatever. I've been through it. All the people been saying what they're going to do: they're going to break my records; they're going to beat me. I've been dealing with it for years now. So for me, it's nothing. I enjoy this.

"I look forward to competing when people talk... because if you don't back it up you look really stupid," said the first man to win six Olympic gold medals in sprinting and an eight-time world champion.

Gatlin, 33, has run the fastest 100m this year and been talking a big game, claiming to be "the man to beat".

Bolt is running the 200m on Saturday as he is focusing on that event this season, frustrating many track fans eager to see how he would measure up in a duel against Gatlin over 100m.

The Jamaican world record holder in the 100m and 200m said he was not yet in shape for a showdown duel but looked forward to it.

"Afraid? When people say that, I laugh. I've been in the sport for years and I've never dodged anybody. When it matters, I've always showed up and shown that I'm the best," Bolt said.

"Fact is, I'm not in the best of shape and I'm not going to put myself out there if I know I'm just coming back and I need time to get back to where I need to be. When I get to Beijing I'll be ready to go and that's when the showdown will be."

Bolt said the suspense of how the sprinters shaped up against one another could help build interest in Beijing.

"People can look forward to the championship. What's going to happen?" he said. "Justin is running good, Tyson [Gay] is running good, Asafa [Powell] is running good, Usain is running good.

"So when we come to the championship, it's going to be like an explosion."