Ireland will attempt to channel Usain Bolt's serene confidence in the triumph of class over form at the World Cup, according to Rory Best.

Bolt surprised the Ireland squad in London before their warm-up clash with England, with the six-time Olympic gold winner dropping in for dinner and a chat.

Ulster hooker Best revealed that Bolt's unstinting confidence shone through as the 29-year-old Jamaican described how he shrugged off patchy form to defeat Justin Gatlin to take his World Championships gold tally to 11 this summer.

Ireland open their Pool D campaign at the World Cup by facing Canada in Cardiff on Saturday after two-straight Test losses, keen to emulate Bolt's ability to transcend recent results on the biggest stage of all.

"I am a big fan of all sports so to meet someone like that was unbelievable," said Best of Bolt's visit to the Ireland camp.

"He is such an iconic figure in the word of sport.

"There wouldn't be many people that would be more recognisable, so it was great just to get his thoughts on things.

"The big thing, from our point of view, was just that he says when he goes into championships and he feels good, he knows he's going to perform.

"It's not necessarily about how events leading into it have gone. It is about how he's feeling himself.

"From our point of view, we're feeling pretty good at the minute. But, obviously, the results over the last two games haven't gone the way we wanted.

"He has a lot of self-belief. He knows when he prepares well and is ready for the tournament he can perform.

"He was unbelievably relaxed.

"The big thing that struck me about him, as a presence, was just how big he is.

"Paulie (Paul O'Connell) went to present him with a shirt and claims that he had an inch on him, but I'm not convinced!"

Bolt was under greater pressure than ever to fend off the challenge of American Gatlin at the Beijing World Championships.

The Jamaica star edged out his chief rival in both the 100 and 200 metres finals, reasserting his global dominance.

Ireland team manager Mick Kearney believes Bolt's mere presence handed head coach Joe Schmidt's squad a lift ahead of the World Cup.

Schmidt's men are chasing a first-ever semi-final at the World Cup, but have slipped to a 16-10 loss to Wales and a 21-13 defeat to England in completing their warm-up schedule.

"One thing that struck me was the lads asked what he did to motivate himself and he said 'I just relax, I listen to a bit of music'," said Kearney.

"He didn't have any major snippets that I'd be willing to share as such but the one of things was that he was just is a completely relaxed individual, very, very laid back but obviously extraordinarily driven to succeed.

"I think to do what he did in the 100 and 200 at the World Championships was pretty awesome because he was big-time on the back foot against Gatlin coming into it.

"Gatlin had the best times and Bolt hadn't been running that well, yet his competitive spirit came out massively and in the couple of hours he spent with us you could probably see why he is successful.

"He is a relaxed guy but at the same time he is very driven as well to succeed."