Wales and Lions coach Gatland has made a total of six changes to his starting XV following Friday night's unconvincing win over Samoa.
2009 Lions James Hook, Leigh Halfpenny, Jamie Roberts, Shane Williams, Stephen Jones, Gethin Jenkins, Matthew Rees, Alun-Wyn Jones, Andy Powell and Martyn Williams all start for Wales, as do 2005 tourists Gareth Cooper and Ryan Jones.
Gatland has reverted to the same starting line up that narrowly lost to the All Blacks a fortnight ago, with one exception.
Scarlets centre Jonathan Davies comes in to earn his first start on Welsh soil in his fourth international, with the 21-year-old replacing the injured 2005 Lion Tom Shanklin as Roberts moves from inside to outside centre.
Uncapped Dragons flanker Dan Lydiate takes a spot among the replacements, as does Ospreys centre Andrew Bishop - a late call up for Shanklin.
Grand Slam winners Ireland are next in line with 10 Lions tourists in their squad to face Fiji, while Declan Kidney has also named a further two players who made Ian McGeechan's original 2009 Lions party but were forced to withdraw through injury prior to departure for South Africa.
Rob Kearney, Brian O'Driscoll, Gordon D'Arcy, Keith Earls, John Hayes, Paul O'Connell, Stephen Ferris and Jamie Heaslip all start having represented the Lions in South Africa, with original Lions selection Jerry Flannery continuing at hooker and 2005 Lion Shane Horgan starting on the right wing.
Munster duo Donncha O'Callaghan and Tomas O'Leary are both included on the bench after O'Callaghan appeared on his second Lions tour and injury cruelly robbed O'Leary of his place on his first.
As for Scotland, new boss Andy Robinson has named the exact same 22 that secured a 23-10 win over Fiji last Saturday as he looks for similar success against Australia.
That means 2005 Lion Chris Cusiter again captains the side ahead of 2009 Lion Mike Blair, with a further two Lions in the starting line up and another among the replacements.
Ross Ford, who missed out on original Lions selection this summer but was called up after Flannery withdrew at the pre-tour training camp, starts at hooker, with Nathan Hines named at lock and 2005 tourist Jason White providing second row and back row cover from the bench.
Wales (vs Argentina, Saturday November 21, kick-off 2.30pm)
James Hook (Ospreys), Leigh Halfpenny, Jamie Roberts (both Blues), Jonathan Davies (Scarlets), Shane Williams (Ospreys), Stephen Jones (Scarlets), Gareth Cooper; Gethin Jenkins (both Blues), Matthew Rees (Scarlets), Paul James, Alun-Wyn Jones (both Ospreys), Luke Charteris (Dragons), Andy Powell, Martyn Williams (both Blues), Ryan Jones (Ospreys, captain)
Replacements: Huw Bennett, Duncan Jones (both Ospreys), Bradley Davies (Blues), Dan Lydiate (Dragons), Dwayne Peel (Sale Sharks), Andrew Bishop (Ospreys), Tom James (Blues)
Ireland (vs Fiji, Saturday November 21, kick-off 5:15pm)
Rob Kearney, Shane Horgan, Brian O'Driscoll (captain), Gordon D'Arcy (all Leinster), Keith Earls (Munster), Jonathan Sexton*, Eoin Reddan (both Leinster); Tom Court (Ulster), Jerry Flannery, John Hayes (both Munster), Leo Cullen (Leinster), Paul O'Connell (Munster), Stephen Ferris (Ulster), Denis Leamy (Munster), Jamie Heaslip (Leinster)
Replacements: Sean Cronin (Connacht)*, Tony Buckley, Donncha O'Callaghan (both Munster), Sean O'Brien (Leinster)*, Tomas O'Leary (Munster), Paddy Wallace, Andrew Trimble (both Ulster)
*Denotes uncapped player
Scotland (vs Australia, Saturday November 21, kick-off 5:15pm)
Rory Lamont (Toulon), Sean Lamont (Scarlets), Alex Grove (Worcester Warriors), Graeme Morrison (Glasgow Warriors) Simon Danielli (Ulster); Phil Godman (Edinburgh), Chris Cusiter (Glasgow Warriors, captain); Allan Jacobsen (Edinburgh), Ross Ford (Edinburgh), Moray Low (Glasgow Warriors), Nathan Hines (Leinster), Alastair Kellock (Glasgow Warriors), Alasdair Strokosch (Gloucester), Johnnie Beattie (Glasgow Warriors), John Barclay (Glasgow Warriors)
Replacements: Dougie Hall (Glasgow Warriors), Kyle Traynor (Edinburgh), Jason White (Clermont Auvergne), Richie Vernon (Glasgow Warriors), Mike Blair (Edinburgh), Chris Paterson (Edinburgh), Nick De Luca (Edinburgh)
Bold denotes Lion