West Coast will go into Friday's clash against North Melbourne with three tall defenders following the omission of Mitch Brown.

It's a slight step away from the line-up of the past fortnight. The Eagles' two wins came with four key position defenders - Brown, Darren Glass, Eric Mackenzie and Will Schofield.

The trio will combine for roles on Drew Petrie, Majak Daw and Aaron Black at Patersons Stadium.

After a rocky start to the season defensively, the Eagles have tightened up. Since Round 2, they haven't conceded more than 90 points in a game, with a season low of 67 in the Round 6 win against the Western Bulldogs.

On the other side of the equation, North heads into the game coming off its highest score since Round 2 of last season, amassing a huge score of 22.19.151 against the Bulldogs.

With that in mind, an intriguing battle looms. Schofield is perhaps the most versatile of the key backs, able to cover more ground than Mackenzie and Glass. For North, Black is the most mobile of the key-forwards, spending a lot of his time up the ground.

Despite playing just three games in 2013 so far, Black ranks sixth in average inside 50's per game at North; impressive numbers for someone whose main task is to hit the scoreboard.

If Black can continue to be a threat both outside and inside 50 (six goals in three games), he may be able to expose Schofield and make him work harder than he would like defensively.

Closer to goal, Glass, in his 250th game, could match up on Petrie. Interestingly, Petrie ranked Glass at number four in his top 10 defenders of the last 25 years during the week.

"He shuts down key defenders by smart use of his body. He's got really good core strength and he's able to push players underneath the footy and off the line of the ball," he said.

Petrie was quiet in all three games against the Eagles in 2012, kicking just two goals total. However in recent weeks he has proved valuable playing more as a decoy forward. Following North's defeat of the Bulldogs, Brad Scott summed up how Petrie can be extremely important to the forward line even when he isn't kicking goals.

"He's the ultimate clubman. He'll do whatever's best for the team and he doesn't see it as a sacrifice. He just sees it as investing in our team.

"Drew was able to give Majak a better opportunity today (referring to Daw's six goal haul) and that's why we were so keen to have him for two more years."

Daw, possibly matched up on Mackenzie, is the last of the three key forwards. The challenge for him is to replicate the effort from last week, even if it doesn't result in the same output in front of the big sticks.

About to play in just his fifth game, Daw has dominated headlines all week as he prepares to face Nic Naitanui in the ruck. However his main role is to provide a strong target deep in the forward line.

If he can continue his budding partnership with Petrie and Black, and the trio cause headaches both in the air and at ground level, North should have the firepower to kick a winning score at Patersons Stadium.