OITA, 17 Oct - Wrestler's son Josh Navidi aims to help Wales take a grip on Sunday's quarter-final against France.
The Cardiff Blues flanker, above, is used to throwing his weight around, having learned a few tricks of the trade from his father, Hedy.
"I have done a bit of wrestling with him. It's probably the hardest training I have ever done," said the 28-year-old, whose father left Iran to study at Bangor University and never went back after meeting future wife Euros.
Navidi senior once finished fifth in the British Open and later coached the Wales and Great Britain freestyle wrestling teams. He is out in Japan to see his son grapple with France in a different sport.
"I hope my wrestling background comes in handy in rugby, all the years with him, messing about, nothing too serious," said Navidi.
"It is nice to have them out here. My brother (Sam) flies out on Friday.
"I haven't actually seen my dad yet, they are still down in Kumamoto. I am sure he will say something just before the game.
"It is nice for them to get out and enjoy it because they don't get away that much - my dad is quite stubborn with flying and travelling.
"It is nice for them to experience it, because my dad is quite a big sportsman. He is enjoying it."
Navidi goes into the game knowing it could be the final one for coach Warren Gatland, who leaves his post at the end of the tournament.
Assistant coaches Shaun Edwards and Robin McBryde are also moving on once Wales are out, and Navidi - who has become a key part of the back row - says they are owed a lot.
"We want them to finish on a high and give them the send-off they deserve.
"Gats' record speaks for itself, with the (three) Grand Slams and all the campaigns he's been part of, and what we've achieved as a nation from the start of his time to where we are now.
"Defensively, Shaun knows what he wants and if you don't do what he wants you get screamed at. Defensively and around the contact area, he has a big focus on that, and he has helped me quite a bit.
"He is quite calm at the moment but does have times when he goes off on one. It's quite funny."
Navidi is confident Wales, ranked No.2 in the world, can live up to their favourites tag and see off France, ranked six places below them, at Oita Stadium to reach the semis, where Japan or South Africa will be waiting.
"Being No.2 is nice recognition but it will mean nothing if we don't win on the weekend," he said. "There is no danger of us being over-confident.
"We're not being big-headed or anything, but we're in a good place and it's about delivering.
"We know each other well and we've been together for a long, long time now. Things are coming thick and fast, but they're coming along nicely."