Spare a thought for versatile St Kilda defender Jason Blake.

The 28-year-old heads into Saturday's AFL grand final against Geelong knowing that he could be playing on either Cats enforcer Cameron Mooney, young gun spearhead Tom Hawkins, the unpredictable Steve Johnson or even the much smaller but arguably the most dangerous of all the Cats' star forwards in Paul Chapman as well as giant ruckman Brad Ottens when he is resting in attack.

While he might stand 189cm the low-profile but highly efficient Blake is equally comfortable playing on giants such as the 202cm Ottens and smaller forwards such as Chapman, who stands just 179cm.

Blake has been a key component of a St Kilda defence that has conceded the least amount of points ever in a season since the competition changed to 22 rounds in 1970 and which during the finals has conceded just seven goals in each of its matches against Collingwood in the qualifying final and the Bulldogs in last week's preliminary final.

The Saints realise that keeping the free-flowing, ultra-attacking Cats - who destroyed Collingwood by 73 points in last week's preliminary final - to such a low score will be a much tougher task particularly with the huge range of contrasting attacking options that the Cats possess.

Blake says he is mentally preparing himself for all kinds of potentially contrasting match-ups on Saturday knowing that at different stages he could be asked to play on just about any of the Cats forwards.

"We have got to prepare for anything and be ready for anything," he said.

"During the week we will prepare for that and hopefully get the job done."

While it was Chapman who destroyed the Magpies with five goals last week, Blake said the Saints cannot afford to become too 'Chappy conscious' on Saturday and are also preparing for the possibility of Ottens playing in attack to try to expose the Saints' defence for height.

"He is very dangerous up there but they have got a number of dangerous players that can kick goals," Blake said of Chapman.

"And he (Ottens) is definitely an option for them (in attack) but I know we have got the calibre of players to deal with that so it won't be an issue."

Blake said the key for the Saints' defence on Saturday was to stick to the same 'team defence' policy that has been so effective for the club this season.

"We have to be really organised and working together," he said.

"They (Geelong) are dangerous and can score quickly so we are going to have to be on the ball."