AFL boss Andrew Demetriou concedes Hawthorn have been unfairly disadvantaged heading into Saturday's grand final by an anomaly in the finals fixture.

The AFL chief executive has also blasted the Western Australian Football Commission (WAFC), saying it is incomprehensible that a rugby union Test in Perth was allowed to compromise the earlier weeks of the finals series.

Demetriou, who tipped Sydney to upset the Hawks by less than a goal, acknowledged Hawthorn had had their preparation for the decider compromised by having a shorter break between games than Sydney.

He said as the minor premiers the Hawks deserved the advantage and the AFL was working to avoid a repeat in future seasons.

The Swans hosted their preliminary final at ANZ Stadium last Friday night, with the Hawks playing a twilight game at the MCG a day later.

Demetriou said with an NRL preliminary final at ANZ Stadium on Saturday night and the SCG below full capacity, the AFL had been left with little wriggle room.

"In fairness to Hawthorn that's absolutely correct, they should have been playing Friday night," Demetriou said on the AFL website.

"Because we didn't have the SCG available with a 50,000 capacity it just left us with little leverage and little option.

"I can tell you when the SCG's at full capacity, if for whatever reason the contractual obligations that they have at ANZ means the ground is not available for the AFL, then we wouldn't compromise the top team.

"We'd play at the SCG and we'd play on the right night."

But Demetriou said the WAFC had been left in no doubt about the AFL's dissatisfaction with a cross-code scheduling fix on the opening weekend of the finals series.

An Australia-South Africa rugby union Test at Patersons Stadium on the Saturday meant West Coast had to host North Melbourne on a Sunday then back up six days later to face Collingwood.

"It compromises our finals, the integrity of the finals. It's incomprehensible to us and we've made the point, that the Western Australian Football Commission could book a rugby union Test in September," Demetriou said.

"AFL football is the biggest tenant at Subiaco, it's helped build that ground.

"We are entitled, after teams play off all year, to know that the ground is exclusively used for AFL football.

"We've made that point clear, we don't anticipate it happening again."