FRIDAY night's clash between the 2015 Grand Finalists shapes as one of the most pivotal games of the home and away season, with top four positions for both clubs on the line. AFL.com.au spoke to an opposition assistant coach who has had some success against both teams to identify the five keys to the match.

1. The Hawks must take away the Eagles' home comforts
The key differences from round two, when Hawthorn beat the Eagles by 46 points at the MCG, is the venue. West Coast is clearly a better team at Domain Stadium where it thrives on stoppages. Away from home, the Eagles have a total clearance differential of -64 from nine games. At home they have been beaten at the stoppages just twice. Nic Naitanui is the most important player on the field on Friday night, with the Eagles reliant on him to give them that stoppage advantage and the repeat inside 50s it creates.

LAST TIME THEY MET: Hawks defeated Eagles by 46 points

2. Who blinks first in game of tag?
It is the style of both coaches to let the opposition's best wingman run free in a game of chicken that could go a long way to deciding this match. Eagle Andrew Gaff and one of Isaac Smith or Brad Hill for the Hawks will nominally be opponents, but they won't go near each other. The Eagles will try to contain Smith or Hill's impact by manning dangerous space at stoppages. The Hawks will set up with a wing 'sweeper' and a stoppage player in a lateral position as their insurance policy. In an emergency, Liam Shiels and Mark Hutchings will be the respective taggers.    

3. The Eagles will force the Hawks down the line
How the Hawks are allowed to move the ball on the skinnier Domain Stadium will be fascinating. The ideal scenario for the Eagles is using their once famed 'web' to force their opponents into a longer kicking game, using the boundary line. This will not only keep the Hawks out of their preferred high-possession game, it will bring Jeremy McGovern into the match as a key-marking player. His ability to read the play and intercept is exceptional and his 2.2 contested grabs a game are well above any other player on the ground. Opposition movement down the line will also force more stoppages.    

MATCH PREVIEW: West Coast v Hawthorn

4. Walking a fine line around the protected area
The 10m protected area around the mark suits Hawthorn to a tee, allowing masterful ball users like Sam Mitchell to mark, pivot and kick in an instant and with less pressure. The Eagles have a fine line to walk on Friday night. They need to force the Hawks off the mark without encroaching from the wrong angle and giving away 50m penalties. If they can't slow down Hawthorn's ball movement by doing this, their defenders will be under severe pressure against an unpredictable forward line. 

5. Hawthorn can't turn for home behind this time
The Hawks won't get out of jail on Friday night. Their ability to come from behind and steal crucial wins has been the story of their season, but West Coast will not let a lead slip, averaging 32.8 points in fourth quarters at home, despite being kept scoreless by Adelaide in round 12. The Hawks need to enter the last quarter in a winning position and maintain their intensity at the hostile Domain Stadium. They were disappointing against Melbourne last week, kicking 1.3 in the fourth term to the Demons' 5.2.

The stage is set for one of the most important games of the season, and both teams will go in knowing exactly what must be done to prevail. The Eagles have been hurt at selection with injury to important young defender Tom Barrass (leg), but their backline has overcome plenty in the past. They should be favoured to prevail at home, but expect a classic battle with all that sits on the line for the unchanged Hawks.  

Isaac Smith and Matt Priddis clash in last year's Grand Final. Picture: AFL Photos