Chapman may not be a capped Wallaby, but for all of his 32 years of age, the former Brumbies player has played alongside a lot of powerful locks in his time - both big and mobile ones at that.

So the 197cm and 110kg forward knows who has the goods and who doesn't.

But a little more than two years on from his first sighting of the 204cm Skelton, Chapman admits that he has been surprised by the Skelton who plays now - despite his 145kg - for a full 80 minutes, as he did again on Saturday in the Super Rugby champion's 18-16 win against the Rebels.

Chapman, who made his first start for the Waratahs on Saturday in the second row with Skelton - playing 47 minutes - totally understands why Waratahs coach Michael Cheika has faith in Skelton.

"The way he gets around is phenomenal for a guy his size," said Chapman. "He is only getting better and better every game. The more he plays the fitter he is getting.

"There is no way he could have played 80 minutes 12 months ago ... Cheika has backed him and 'Cheik' believes in him and he is doing really well."

Besides his improving work at set piece, Chapman believes Skelton has developed into a top ball-running forward.

"It takes two or three defenders to bring him down," Chapman said.

"You have got to mark him every time and if they use him in back play it is going to suck a couple of guys if you go out behind him. He is a really good attacking weapon for us."

Chapman will even go as far as to say that Skelton is showing himself to be unique.

"You can't really compare him to many second rowers I have played with," he said.

"[It is] just his dimensions purely. [They are] not comparable. He is phenomenal.

"When I first came here I had never heard of him before. He was standing at training one day - and I wasn't even in the squad - and just couldn't believe the size of him."

Pressed on 22-year-old Skelton's potential, Chapman said: "[It is] untapped at the moment really, but you've got to remember he is so young.

"At this level and Test footy, if he can be an 80 minutes player ... that's a phenomenal thing to have for a guy that size.

"No one in world rugby could really boast that."

For Friday's blockbuster against the Brumbies in Canberra, Chapman said the Tahs cannot afford to take their foot off the pedal as they did against the Rebels after gaining early domination.

"The Brumbies played well again on the weekend after a loss to the Rebels ... It is going to be big clash. There is a lot riding on it – top of the Australian conference."

The Waratahs and Brumbies have both said the gay slur issue that marred their last clash in Sydney, in which Jacques Potgieter used the term "faggot" against some Brumbies players, has been laid to rest. But it remains to be seen what reception the South African backrower will receive in Canberra.

Asked if Potgieter could be in store for a hot reception in Canberra, Chapman said Potgieter will always "potentially" receive a hostile welcome when away. "All the away games, the crowd either loves him or hates him. He's that sort of figure. I know what you are alluding to. I would say so.

"No doubt people will potentially draw on that sort of thing, but it's not an issue to us.

"It has been dealt with and Jacques made his apologies and has moved on."

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