Coach Joe Schmidt has made four changes to the starting side that overcame the Pumas 20-19, with No.10 Noah Lolesio ruled out of Saturday's (0500 Sunday AEST) match with back tightness.
Donaldson replaced Lolesio in the final minutes of the first Test at La Plata and kicked the last-gasp penalty to secure the victory.
Ben Donaldson takes over the No.10 jumper from the injured Noah Lolesio to face the Pumas. (James Gourley/AAP PHOTOS)
Schmidt said it was another opportunity for Donaldson, who wore the World Cup five-eighth jersey, to prove himself while youngster Tom Lynagh has been included on the bench.
"We're still trying to build our way forward and I think it's a great opportunity for Ben Donaldson," Schmidt said from Sante Fe on Friday morning (AEST).
"He was the incumbent, really, from the World Cup, and it's a great opportunity for Tom Lynagh after having a hamstring niggle that he was struggling to get rid of.Â
"He's now 100 per cent and so those two, they're excited to take on the mantle."
Fullback Tom Wright has also been omitted with an ankle injury which has created a backline shuffle with Andrew Kellaway moving from the wing into the No.15 jersey, and 20-year-old speedster Max Jorgensen earning his first start in his third Test.
Schmidt praised the acceleration and footwork of the young Waratah, whose dad Peter played two Tests.
"Max has built his way in - he's had a couple of runs off the bench, which is ideal for him to gain a bit of confidence and for us to know a little bit more about him," Schmidt said.
"He's working really well off the ball which was part of what we wanted him to work on, because once he's on the ball he's an exciting young rugby player."
The only change to the starting forward pack is Western Force skipper Jeremy Williams replacing injured lock Lukhan Salakaia-Loto (shoulder), while No.8 Harry Wilson will captain the side for a second straight week.
Melbourne lock Josh Canham is in line to become Wallabies' 16th debutant of the year after being named on the bench.
Wallabies coach Joe Schmidt (left) is a big fan of James Slipper (right) ahead of his 139th Test. (Darren England/AAP PHOTOS)
Slipper, 35, will also start in the reserves after he was unavailable for the first Test following a late arrival into Argentina due to the birth of his second daughter.
Already the world's most capped prop, he will draw level on 139 Tests with former captain and halfback George Gregan.
"It's great to have him back in the mix this week and that big number is looking pretty promising," said Schmidt.
It's a tremendous achievement for James to equal the record of the most capped Wallaby.
"He's the ultimate team man and I know the whole group will do everything they can to make it a memorable milestone."
The past two Wallabies Tests have been played in heavy rain but the forecast for the afternoon Sante Fe match is 28 degrees and sunshine.
Schmidt said he'd take any win he could get.
"It was eight degrees last Saturday so it's a 20 degree swing, and hopefully the result doesn't swing," Schmidt said.
"We'll just keep trying to stack good elements of performance together, and hopefully that's enough to get us the result.
"We'll take a result in the last minute by one point any time that's on offer.
"I'm not sure my heart will sustain those, but certainly it was a real fillip for us last week to get the result."
Wallabies: Andrew Kellaway, Max Jorgensen, Len Ikitau, Hamish Steward, Marika Koroibete, Ben Donaldson, Jake Gordon, Harry Wilson (capt), Carlo Tizzano, Rob Valetini, Jeremy Williams, Nick Frost, Taniela Tupou, Matt Faessler, Angus Bell. Res: Josh Nasser, James Slipper, Allan Alaalatoa, Josh Canham, Langi Gleeson, Tate McDermott, Tom Lynagh, Josh Flook.
