Lyon is the leading spinner in this Ashes series and not only does he have 11 wickets so far, behind only Mitchell Starc for the series, but he heads all bowlers in Test cricket this calendar year with 57 scalps. He is in sublime form, with Sri Lankan great Kumar Sangakkara declaring him "the key difference between the two sides" in a recent Wisden column.

But when you think of Perth, you think of Lillee and Thomson off the long run, or Curtly Ambrose's seven wickets for one run. Only four spinners have bagged five-fers in WACA, with Bruce Yardley the only Australian among them. The great Shane Warne never managed more than four wickets in his 21 Test innings there, and Lyon has taken just 12 wickets in four Perth Tests at an average of more than 50.

He may be the Greatest Offie of All Time, but Lyon won't be bowling on a goat track in Perth.

And yet, as former England off-spinner Vic Marks observed in his musings in The Guardian: "It feels unprecedented before a big match at the WACA that batsmen should spend time fretting about playing against an off-spinner."

Lyon has taken 11 wickets in this series, 10 of them left-handers, and Marks believes that his flight and dip will continue to present a threat, regardless of the amount of turn he extracts from the WACA pitch.

It is a sentiment supported by coach Darren Lehmann, who suggested Perth was "a tough place (for spinners) ... but Nathan will get drift obviously with The Doctor [Fremantle's famous sea breeze] and some bounce".

But one man well placed to forecast what Lyon can expect is WA finger spinner Ashton Agar.

The 24-year-old left-armer, who has played four Tests for Australia, predicts Lyon will still bowl plenty of overs in Perth, but will be bracing himself for more of "a supplementary role", albeit a crucial one.

"Playing Shield cricket here the past few years I've hardly seen a ball ever spin," Agar said. "So I don't expect to see it spinning at all this week.

"I wouldn't say the WACA is a spinner's graveyard, it's just the role of a spinner is very different in Perth.

"Successful teams have tended to use their fast bowlers a lot at this ground, and they get the wickets. But a lot of bowlers who have played vital roles in Perth have played more of a holding or restricting role, going at two runs an over or less without necessarily taking any wickets.

"The only time Perth usually gets harder to bat on is by about day four when cracks start to open up. But even then captains are more tempted to use their seamers to exploit that, rather than spinners."

Agar believes captain Steve Smith will set more defensive fields for Lyon's bowling, "because he will be less likely to create those catches around the bat".

"I think in Perth you'll be more likely to see a lot of the Englishmen get out cutting, getting caught behind the wicket because there's been more bounce than they expected. A lot of the English guys have got out like that in the practice matches."

He also predicted Lyon might create some chances with a deep long-on, because some batsmen would "fancy themselves to take on the shorter straight boundaries".

Agar said the Fremantle Doctor "certainly got spoken about a lot ... but Nathan's getting so many revs on the ball he's going to get drift and nice drop no matter where he bowls".

He felt certain the WACA curators would have been "trying to produce the hardest, fastest pitch that they can to suit the Aussie quicks, but I also know that they've been trying to prepare similar wickets for the Shield matches and it hasn't necessarily worked out like that.

"I've seen a few balls that haven't carried to the keeper this season. They've been really flat wickets that haven't really broken up."

Regardless of how the WACA Ground pitch plays in its final outing before Test cricket shifts five minutes up the road to the new Optus Stadium, Agar is convinced Lyon will bowl with supreme confidence.

"From a personal point of view the outcome might be a little different for him, but I expect the process will be exactly the same," he said.

And no matter how many overs he bowls or wickets he takes, Lyon will hope he gets the chance to fulfil another of his key responsibilities within the team, the man who leads the chanting of "Under the Southern Cross I Stand" after a victory.

FIVE-WICKET HAULS BY SPINNERS IN WACA TESTS:

6-84 Bruce Yardley v Pakistan 1981

6-87 Dan Vettori v Australia 2001

5-89, 5-105 Bishan Bedi v Australia 1977

5-92 Monty Panesar v Australia 2006 5-107 Bruce Yardley v England 1982.