I WILL be really interested to see which end Campbell Brown starts for Hawthorn against Collingwood tonight. Back or forward?

It will be a postscript to a big statement from Alastair Clarkson last Friday night, which confirmed an emerging football trend that defensive pressure is now a cornerstone of every game plan. Or should be.

In the Hawks' biggest game of the year last week against Geelong, Brown, an All-Australian defender, was deployed in a defensive role in the forward line.

It was a three-pronged defensive attack, as Brown shared the harassment duties inside the Hawthorn forward 50 with chase-down specialist Cyril Rioli and elevated rookie Cameron Stokes, who was recalled for just his fifth AFL game and his first since round 4.

Why? Because Clarkson clearly believes that much of the Geelong drive comes via the run off the back six. And that if his players can put pressure on the Cats coming out of the back half and prevent them delivering the ball quite so perfectly to the midfielders it's a big thing. And rightly so.

This is an extension of an under-recognised pillar of the Brisbane Lions' success of 2001-02-03. Craig McRae was never one of the public pin-up boys of the Lions side but, internally, his role of chasing, harassing and tackling inside our forward 50 was treasured by coaching staff and teammates alike.

His No.1 key performance indicator wasn't goals or possessions — it was tackles. It was all about trying to influence the way the ball rebounded from our forward line.

The same applied to Shaun Hart. They were two little men with a giant role to play. And it's now a widespread philosophy, which is becoming more and more important in the modern game.

If outsiders listed the Geelong players in order in terms of importance, Matthew Stokes would struggle to get into the top 18, such is the pure class of the Cats. Yet I suspect his defensive responsibilities up forward elevate his standing within the group. It is perhaps not quite as important to Geelong because they are so damn good on every line, but at every other club, the role of the defensive specialist in the forward line is crucial.

It's almost uncanny, too, how many of these jobs fall regularly to the indigenous boys. And how well they do it. So gifted and exciting with the ball in their hands, they are adding a new dimension to the game with their defensive pressure.

Rioli, a magician in his first year, is building a career at Hawthorn around his ability to upset opposition players in this fashion. And that after Aaron Davey made it a trademark at Melbourne.

Lindsay Thomas and Matthew Campbell have been sensational in this role at North Melbourne. Likewise Eddie Betts at Carlton, Alwyn Davey and Andrew Lovett at Essendon, and Rhan Hooper at Brisbane.

These players share blistering pace — an important attribute in what is fast becoming one of the most important roles in footy. But speed is not the only pre-requisite.

As much as anything, it is about intent. About opposition players knowing that someone will be coming and feeling the pressure before it gets there.

One of the most devastating plays in the game these days is the bad clanger inside forward 50 because it allows the opposition to set up a forward thrust almost unopposed. The ball is gone in a flash, and how quickly a team can regroup and give their midfielders and defenders even half a chance to man-up is pivotal. Fundamental to that is forward-line pressure.

Small forwards have got to be able to win the ball, too. And goals are an important bonus. That's why Hooper lost his spot in the Brisbane side last week. His defensive work had been terrific, but he'd lost that difficult balance with attack.

It's not exclusively a little man's job either. Mitch Hahn at 188 centimetres and 99 kilograms is the man with the defensive pressure intent in the predominantly smaller Bulldogs forward line.

He is not overly quick but the first thought of this under-rated Queenslander, whenever the Dogs lose possession up forward, is to chase it down in his bullocking fashion. To him, it is all about desire.

Likewise Hawthorn's Brown, who over the past two years has played above his height and weight with terrific results in the back half.

That Clarkson was prepared to sacrifice his presence in the back line to utilise his chasing, tackling and pressuring in the forward line, and to keep the Geelong defenders honest, says an enormous amount about how Hawthorn think they can beat the hot flag favourite.

I suspect Brown will go back to his traditional role tonight. But watch for him to play forward again if the Hawks come up against the Cats again. It's a strategy that certainly influenced last week's game and I'm sure the Hawks hope it can have a similar effect in September.