Bernard Foley is in line for his Test debut with an ankle injury threatening to rule Wallabies back Matt Toomua out of their Rugby Championship Test against Argentina.

Reserve five-eighth Toomua strained ligaments in the joint after coming off the bench during the second half of their 20-point defeat to South Africa in Cape Town last weekend.

The marathon plane and bus journey from there to Rosario, north of Buenos Aires, didn’t help.

Wallabies coach Ewen McKenzie said he would give Toomua until Wednesday before he made a call.

Should Toomua be ruled out, Waratahs No.10 Foley will come on to the bench.

“He rolled his ankle but it has progressed well,” McKenzie said.

“We’ll see what happens tomorrow (Wednesday morning) when we train, we’ll see what progress he has made.

“The swelling has certainly come down. He is the only one in any sort of doubt.”

The Wallabies are desperate to avoid the Rugby Championship wooden spoon, which they could be left holding with a loss to the Pumas.

There are only two points which currently separate the teams in the standings.

The Australians edged Argentina by one point in their earlier meeting in Perth but have lost all four matches against competition leaders New Zealand and South Africa, as have the Pumas.

Prop Ben Alexander said the players felt the pressure to win on Saturday.

Last year Rosario the Wallabies triumphed 25-19 in a rugged encounter played in front of a sell-out crowd of 41,000 at the Estadio Gigante de Arroyito.

An old-school concrete arena, Alexander said it made for a formidable yet memorable occasion.

“We haven’t won many games this year so we’re very hungry for success and this is a massive game,” he said.

“Any of the guys who played here last year will know it’s a huge occasion to play Argentina in Argentina and the win last year definitely ranks up there with one of my favourite wins of my career.”