Ricky Stuart's England Rugby World Cup invitation baffles Michael Cheika

Wallabies coach Michael Cheika can't fathom why England would invite Canberra Raiders NRL coach Ricky Stuart into their camp ahead of their biggest game in four years.

England counterpart Eddie Jones has opened the doors for Stuart to observe his team up close as they prepare for Saturday's World Cup quarter-final against Australia in Oita.

It mirrors a similar overture to another league great, Andrew Johns, to speak with English players ahead of sweeping the Wallabies 3-0 in their 2016 series in Australia.

Cheika said Stuart's invitation would be the equivalent of him inviting England soccer coach Gareth Southgate, who he does know personally, into the Wallabies camp this week.

"It must be weird for the players having an Aussie because Ricky is a legend," Cheika said

"It'd be like... I'm friends with Gareth Southgate, I don't know if I'd be wanting him in here the week that we're playing England.

"Obviously they (Jones and Stuart) would be mates I imagine, so it's all good."

Stuart's trip to Japan comes just over a week after his Raiders were beaten by the Sydney Roosters in their first trip to an NRL final for 25 years.

Stuart was a junior rugby union star and played three tour matches for the Wallabies in 1987 before switching codes and becoming a halfback great in rugby league with Canberra, NSW and Australia.

Stuart was to join England during the second half of their fortnight-long build-up to the knockout phase, having had their final pool match against France cancelled because of the typhoon that struck Japan on Saturday.