"It's a fantastic achievement," said Jenkins. "Gareth's been a great example for all players and is the epitome of a quality professional. You wouldn't bet against him breaking through the 100-cap barrier with two games on this tour, three summer matches and then the Rugby World Cup just around the corner.
"His experience and enthusiasm is on display for everyone to see in training and he has a renewed sharpness and edge to his game that can only benefit this Wales team. He was inspirational after missing the first four matches of the RBS Six Nations this year and he leads a team bubbling with international experience into a match we are looking to win."
The versatile Thomas, who is standing in as captain ahead of the rested Stephen Jones, has been chosen on the right wing to provide vital experience in the back three alongside Chris Czekaj and Lee Byrne. With Thomas switching to the flank having started at inside centre in the RBS Six Nations victory over England last time out, there's a call-up for Sonny Parker who partners Jamie Robinson in midfield.
Colin Charvis returns from fifteen months in the international wilderness to pack down on the blindside flank for his 85th cap, where he's joined in the backrow by fellow flanker Gavin Thomas and the Ospreys' Jonathan Thomas.
Despite the absence of the vast majority of Wales's first choice team, with some 16 players staying at home to work on their conditioning, the pack has has plenty of experience in it. There are three Grand Slam stars in Brent Cockbain, Robert Sidoli and Adam Jones, while RBS Six Nations hooker Matthew Rees is joined in the front row by his fellow Scarlet Iestyn Thomas.
Michael Owen is named on the bench, where he will be alongside Gavin Henson as the Ospreys star prepares to play his first rugby since mid-January after finally shaking off a persistent knee problem.
"Gavin is another player we will need to have a close look at," said Jenkins. "We felt we needed to introduce him slowly, but he is likely to play a part in the game at some stage and we can further assess his progress then. He has to play rugby sooner or later and he has been going well in training, full of smiles and really helping to energise the squad."
Also named the bench is prop Ceri Jones and flanker Scott Morgan, who are the only uncapped players in the squad. Jenkins added: "This team has a huge incentive with Rugby World Cup squad places up for grabs. Both sides will also be looking for victory in order to gain a psychological advantage before we meet in the Rugby World Cup."
Wales: L Byrne (Ospreys); G Thomas (Toulouse, capt), J Robinson (Blues), S Parker (Ospreys), C Czekaj (Blues); J Hook (Ospreys), M Phillips (Blues); I Thomas (Scarlets), M Rees (Scarlets), A Jones (Ospreys), B Cockbain (Ospreys), R Sidoli (Blues), C Charvis (Dragons), J Thomas (Ospreys), G Thomas (Scarlets)
Replacements: R Hibbard (Ospreys), C Jones (Harlequins), M Owen (Dragons), S Morgan (Blues), G Cooper (Dragons), C Sweeney (Dragons), G Henson (Ospreys)
Australia: J Huxley (ACT); M Gerrard (ACT), S Mortlock (ACT), A Ashley-Cooper (ACT), D Mitchell (WF); S Larkham (ACT), M Giteau (WF); M Dunning (NSW), S Moore (QLD), G Shepherdson (ACT), N Sharpe (WF), M Chisholm (ACT), R Elsom (NSW), W Palu (NSW), P Waugh (capt, NSW)
Replacements: A Freier (NSW), B Robinson (NSW), D Vickerman (NSW), S Hoiles (ACT), G Smith (ACT), G Gregan (ACT), S Staniforth (WF)
Referee: Jonathan Kaplan (SA)