Rugby: The breakout player of the Rugby Championship

Facundo Isa of Argentina challenged by Teboho Mohoje (R) of South Africa during the Rugby Championship match between South Africa and Argentina. Photo / Photosport

The Wallabies have identified power-running Argentinian Facundo Isa as the man most likely to cause an upset at Twickenham this weekend, with Dean Mumm saying it'd be "silly not to target him."

While Argentina teams have typically been built around powerful scrummaging and control of the game through set pieces, backline flair blossomed during last year's World Cup.

And Isa, the 23-year-old back-rower, is a product of that free-flowing style which captures the eye of fans and teases defensive lines, but he has an outstanding workrate to boot.

A terrific runner of the ball, Isa has made a habit of finding the tryline during the Rugby Championship - adding a try against the world champion All Blacks last week to his five-pointer against Australia in Perth a fortnight ago.

Versatile Australian forward Mumm says he expects Isa to feature heavily in coach Michael Cheika's plans at training this week - despite the 110kg threat being in doubt after picking up a leg injury near the end of the loss to the All Blacks.

"He's a terrific ball carrier in the way he gets himself involved to carry, it's certainly a key aspect of his game," Mumm said on Tuesday.

"It'll be silly not to have some sort of aim or target on him (although) he's certainly by no means the only threat in this Argentinian side.

"He carries and offloads and presents threats everywhere.

"He's a top quality ballplayer and if you want to stop momentum then he's a key person."

Rookie prop Tom Robertson, though, said the scrum remains the key area to contain - even if the Pumas game has evolved.

"They've always been renowned for their scrum, developed more facets of their game nowadays," Robertson said.

"They're still a dominant force in that area so we'll definitely have to look after that.

"I guess after we won in the last match they'll definitely want a bit of vengeance and come out better prepared."

- AAP