The Wallabies will play Australian rugby union's biggest match of the past decade when they take on the Lions at ANZ Stadium in Sydney on Saturday night.

The winner will claim the Tom Richards Cup and bragging rights until the next tour in 2025.

Seven Brumbies will line up in gold - the club's biggest contingent in an international match in three years.

Six of them - including comeback king George Smith, Ben Mowen, Ben Alexander, Stephen Moore, Christian Lealiifano and Joseph Tomane - will be in the starting XV.

It was the same number of Brumbies in the starting XV 12 years ago, when Harrison, Joe Roff, George Gregan, Andrew Walker, Owen Finegan and Smith lifted the Wallabies to a historic win.

Smith will become the first Wallaby of the professional era to play in two series against the Lions.

Only two years ago the Brumbies had just three players in a 30-man Wallabies training squad.

Now they're preparing to play Super Rugby finals for the first time in eight years and a victory against the Lions - the best players from Britain and Ireland - would be the perfect warm-up.

''There's a certain amount of synergy with the strength of Australian rugby coinciding with the strength of ACT rugby,'' Harrison said on Friday.

If anyone knows how one moment from a Lions series can define a playing career, it's Harrison.

The lock was making his debut in the third Test in Sydney in 2001.

The Wallabies held on to a six-point lead with just two minutes remaining when the Lions had an attacking lineout five metres from the try line.

Harrison stepped up and etched his name in rugby folklore. He snatched the ball at the lineout and

got the Wallabies out of trouble. The Wallabies held on to win 29-23 and claimed the series.

It's a moment regularly replayed and has been a thorn in the Lions' side since.

''I don't think I've ever felt more wanted in my life, normally it's the judiciary panel wanting to speak to me instead of getting nice stories,'' Harrison said.

''Selective memory and nostalgia has allowed me to get a lot better than I was. I'm just happy I was part of a good series.

''My biggest fear was not being able to contribute … I was just lucky enough to be in a position to influence the result.''

The Wallabies will channel Harrison - who coaches in France - for one last surge to topple the Lions.

For the Brumbies, it will be emotionally draining, and followed by a finals campaign in Canberra.

But the game marks a turnaround at the Brumbies after a disastrous 2011 season, which was the worst in the club's history.

Coach Jake White has taken over and invested in unknown talent instead of established stars.

Now it's paying off. Rookie Jesse Mogg was plucked from Canberra's club competition before making his Super Rugby debut last year.

Two weeks ago he was watching the first Test against the Lions from a pub in Dickson. Now he's preparing for the biggest moment of his career.

Mowen made his Test debut last month after eight years on the outer.

''The part that has hit me is this is the only series against the Lions I will play in, you're responsible for the result for the next 12 years,'' Mowen said. ''That's why this will go to the next level. We all want the memory of having a beer out of the Tom Richards Cup having won it, not sitting in the dressing room wondering what could have been.''

And Harrison's advice: ''I'm not foolish enough to think I can influence these guys with whatever I say … These guys don't need anything from me they don't already have.''