All Blacks legend Jonah Lomu has delivered some stark advice to rising star Sonny Bill Williams - don't let the hype go to your head and concentrate on delivering for your team mates on the field.

Lomu, regarded as Rugby Union's first global superstar, said the buzz surrounding Williams ahead of the World Cup could prove distracting for a player who has not yet cemented a place in New Zealand's starting line-up.

Rugby League convert Williams has been touted as "the new Lomu" since his All Blacks debut late last year, but the real Lomu said he had seen it all before.

"Mate I've been hearing the new Jonah for how long? For me, it doesn't bother me," Lomu told reporters in Rarotonga during a South Pacific trip to promote this year's World Cup in New Zealand.

"I don't have to roll my eyes or nothing, I know who I am, I'm Jonah Lomu and he's Sonny Bill."

Williams, 25, was a star in Australia's NRL Rugby League competition before defecting to union. His electrifying skills have drawn comparisons to Lomu even from his Canterbury Crusaders Super Rugby coach Todd Blackadder.

But Lomu said incumbent All Blacks' centre Ma'a Nonu, far from a spent force, still threatened to keep Williams out of New Zealand's starting 15.

"He's going to have to fight for his position and I know Ma'a ain't going to give it up lightly," he said.

Lomu, 36, who made his All Blacks debut at 19 and starred in the 1995 and 1999 World Cups before his career was cut short by a rare kidney disease, said Williams had to back up the plaudits on the pitch.

"The thing is he still has to do what he does on the field. There's enough media hype but you've got to leave it on the field," Lomu said.

"We can all talk about it and everything else but he's one person in a team and it's about the team."

Lomu said he went through a similar process when his time in the spotlight threatened to overshadow the contribution of his All Blacks' teammates.

He said Williams, who has drawn the ire of some All Black supporters by pursuing a career in boxing in the lead up to the World Cup, was not bigger than the team.

"He won't be able to shine without the other players, it's exactly the same thing that I had to go through," Lomu said.

"As much as you can be a media star or do whatever sport you like, at the end of the day, you've got to perform on the field and when you get into that All Black environment, you're with the best of the best."

AFP