Cubelli was one of four changes Pumas coach Daniel Hourcade made to his side for Saturday's Rugby Championship clash with the Wallabies in Perth.

The 51-Test halfback played with the Brumbies in Super Rugby this year and Cheika believes it is his time on the inside that gave him the edge over Martin Landajo this week.

"Cubelli we know, obviously a great player, I'm sure they given him that start so he can stick it to his Aussie colleagues," Cheika said.

Cubelli, however, said the decision was more to do with resting Landajo than having inside knowledge on Wallabies players.

"It might be one of the things but at the same time it is a long year," Cubelli said. "There's some games not everyone is going to be capable of playing. It was going to be good for me to have a game on Saturday and rest Martin.

"The last three games I've been off the bench. The squad is very competitive. We are all looking forward to trying to do what we are capable of."

Elsewhere, the Pumas have been boosted by the return of flanker Juan Manuel Leguizamon, who missed Argentina's 57-22 loss to New Zealand in Hamilton.

Hourcade was also forced into making two changes because of injuries to centre Juan Martin Hernandez and lock Guido Petti against the All Blacks.

Santiago Gonzalez Iglesias replaces Hernandez at inside centre alongside Matias Moroni, who moves in from the wing to complete the midfield partnership.

Lucas Gonzalez Amorosino comes in for Moroni out wide, while centre Matias Orlando drops to the bench.

Javier Ortega Desio, who stood in for Leguizamon in the back row last week, moves to lock in place of Petti.

Cheika said Iglesias and Hernandez were both strong defenders, and called Leguizamon, whom he coached at Stade Francais, a "class player".

"They're going to be very mobile and I'd suggest there'd be a lot of running in this game. The ball's going to move around a fair bit."

The Pumas want to turn around a recent habit of falling off in the last 20 or 30 minutes of games. They were neck and neck with the All Blacks last week until the 50th minute, after which the world champions piled on five unanswered tries.

"Some games we keep the intensity but most games we don't do it and we need to improve on that," Leguizamon said.

"We know the Wallabies are good at the breakdown and they have a couple of players that are very good, we need to be careful."

Team: 15-Joaquin Tuculet, 14-Santiago Cordero, 13-Matias Moroni, 12-Santiago Gonzalez Iglesias, 11-Lucas Gonzalez Amorosino, 10-Nicolas Sanchez, 9-Tomas Cubelli, 8-Facundo Isa, 7-Juan Manuel Leguizamon, 6-Pablo Matera, 5-Matias Alemanno, 4-Javier Ortega Desio, 3-Ramiro Herrera, 2-Agustin Creevy, 1-Nahuel Tetaz Chaparro.

Replacements: 16-Julian Montoya, 17-Lucas Noguera, 18-Enrique Pieretto, 19-Marcos Kremer, 20-Leonardo Senatore, 21-Martin Landajo, 22-Gabriel Ascarate, 23-Matias Orlando.