The Waratahs are unmoved by public outrage over their decision to ban Brumbies mascot Brumby Jack from the Allianz Stadium sideline on Saturday night.

Brumby Jack will be forced to buy a ticket to the biggest Australian rugby derby in more than a decade and will sit in the stands with fans after NSW officials denied his request to canter up and down the sidelines in a hotly anticipated showdown with Waratahs mascot Tah Man.

The Waratahs have sold almost 35,000 tickets for the blockbuster clash against the Brumbies in Sydney, with the winner advancing to the Super Rugby grand final next week.

It is the first time since 2002 that two Australian teams have gone into battle in a finals match and the Waratahs appear to be willing to go to any length to protect their unbeaten run at home this year.

Waratahs chief executive Jason Allen confirmed there was no room for Brumby Jack in the arena and dismissed criticism of the organisation's tough stance.

"This is all a bit of horseplay,'' Allen said. ''The stadium bylaws prohibit animals, and that includes horses.

"The answer to all requests for free tickets for this match has been neigh. Brumby Jack can buy a ticket like everyone else."

Brumby Jack was invited to AAMI Park in Melbourne this year to pump up the crowd for the game against the Rebels.

The Brumbies confirmed their mascot would be part of the travelling party, but it is believed to be the first time a visiting mascot has been denied on-field access.