The Wallabies have been dealt a cruel late injury blow for the second straight week with Michael Hooper ruled out of their clash against Argentina with a hamstring injury.

David Pocock shifts to openside flanker in Hooper's absence and will skipper the side while Pete Samu has been called into the starting XV to line up at No. 8 for the second week in a row.

Ned Hanigan will take Samu's place on the pine.

The Wallabies skipper tweaked his hamstring in the win over South Africa but laughed off any suggestion of an injury when asked post-match.

He trained on Tuesday and showed no signs he had slowed down, making Friday's announcement a shock.

Wallabies coach Michael Cheika said Hooper had begun to notice the issue on Thursday and the team opted to take a cautious approach to the twinge.

The 26-year-old has missed a month of rugby already this year after suffering a hamstring injury in the third June Series Test against Ireland.

"He felt his hamstring a bit at training yesterday afternoon and with his recent history, we just thought it was best not to push it," he said.

"He was really keen to play this weekend but a week off will be a good thing for him to just get it right," Cheika said.

This will be Pocock's first match as skipper since the 2016 Test against France when Hooper was rested.

The Wallabies have won 24 of the 37 Tests where Pocock has started at openside.

More to come.

The Wallabies will host the Pumas at Cbus Super Stadium on Saturday September 15, kicking off at 8pm AEST, LIVE on FOX SPORTS, Channel Ten, Macquarie Radio and RUGBY.com.au RADIO. Buy tickets here.

TEAM

IN: Israel Folau, Sekope Kepu, Adam Coleman, Nick Phipps

OUT: Michael Hooper, Tom Robertson, Tom Banks, Joe Powell

Wallabies to take on Argentina

1. Scott Sio (48 Tests)

2. Tatafu Polota-Nau (85 Tests)

3. Allan Alaalatoa (26 Tests)

4. Rory Arnold (16 Tests)

5. Izack Rodda (10 Tests)

6. Lukhan Tui (10 Tests)

7. David Pocock (c) (72 Tests)

8. Pete Samu (6 Tests)

9. Will Genia (93 Tests)

10. Kurtley Beale (77 Tests)

11. Marika Koroibete (14 Tests)

12. Matt Toomua (36 Tests)

13. Reece Hodge (30 Tests)

14. Israel Folau (66 Tests)

15. Dane Haylett-Petty (24 Tests)

Reserves

16. Folau Faingaa (2 Tests)

17. Sekope Kepu (96 Tests)

18. Taniela Tupou (5 Tests)

19. Adam Coleman (25 Tests)

20. Ned Hanigan (14 Tests)

21. Nick Phipps (66 Tests)

22. Bernard Foley (61 Tests)

23. Jack Maddocks (3 Tests)