FIRST as Fitzroy teammates, then as good friends with coaching aspirations and, for three years, as co-conspirators in their roles as senior coach and assistant at the Swans, Paul Roos and Ross Lyon have remained in close contact.

"We've probably been on the phone on a weekly basis for 20 years," says Lyon of a friendship that endured Roos' move from Fitzroy to Sydney.

But as they prepare to meet for the first time as rival senior coaches when the Saints host the Swans on Saturday night, Lyon is not expecting much pre-game banter.

"We'll probably just go about our own business," Lyon says. "We might see how the kids are going. If we do talk, we'll have a bit of a chuckle about how everyone is building it up." Lyon acknowledges that his new job has slightly altered the dynamics of the relationship. "You have to be a bit more cautious sometimes about the things you can and can't say," he says.

For his part, Roos says he will probably call Lyon later in the week — not wanting to break the habit because of a mere game. "I feel like our friendship overrides anything else," he says.

But since Lyon took the St Kilda job, Roos says a few subjects have been off limits. "I don't want to sound like a Nick-Know-It-All, telling him how to do his job or making unwarranted observations, so I probably try not to ask too much about his team," he says. "I don't want him to think I'm prying or to feel he has to hide things."

The big question on Saturday night is whether Lyon's inside knowledge will give the Saints an advantage in a battle between two clubs sitting at 3-3 and desperate to get on the positive side of the ledger.

As Swans' midfield coach, Lyon was given much credit — or, from the AFL, the blame — for Sydney's game plan, particularly its ability to create and win stoppages. Such an intimate understanding of the Swans' tactics and personnel would seem to provide a big edge.

But Lyon claims he is the man who knows too much. "It might be a disadvantage because they've changed a few things this year and sometimes you can have too much information," he says. "Anyway, the whole world knows how Sydney play but not many teams beat them." Lyon says the one piece of advice Roos gave him before he left Sydney was to "be true to yourself".

Yet many experts believe Lyon is trying to replicate elements of the Swans' game plan at St Kilda, particularly by making the Saints more accountable for opponents and competitive at stoppages.

But while Lyon says he is drilling his team in the fundamentals, he denies he is creating St Sydney. "People are getting carried away with that and I think it's been a little bit unfair," he says. "The statistics show we are playing differently. They have almost double the stoppages we do. We're playing a more up-tempo brand of footy. Our forwards are different, our midfield is different."

Accordingly, Roos believes Lyon's big advantage is not his knowledge of the Swans' game plan but that, as a new senior coach, no one has had time to work him out. "It might work the other way," Roos says. "Not that he knows what we are doing but that none of us know what he has put in place."

One thing Lyon will not do is underestimate the Swans, a mistake he says was made too often during his time in Sydney. While Roos managed to successfully sell his team as a bunch of overachievers, Lyon shatters that myth.

"To me, everyone underrates the Swans and their star content," Lyon says. "They've got eight or nine of the best players in the competition. You go through them — Hall, Goodes, Kirk, O'Loughlin, O'Keefe and so on. That's a fact you can't dispute, they are an elite team. And with Everitt and Jolly, they've probably now got the best ruck combination in Australia."

It is the topic for a good conversation. But not the one Roos and Lyon will have this week.