A no-alcohol policy will be in place at today's rugby clash between Christ's College and Christchurch Boys High in Christchurch.
The annual grudge match has previously been the scene of numerous arrests, with inter-school rivalries getting out of hand.
Senior Sergeant Stewart Munro said police would be operating a breathalyser at the gate, and anyone who had consumed alcohol would be barred.
"It's pretty clear, the school don't want anyone who's been drinking to enter their school grounds, and that's their right to do that," he told Newstalk ZB.
Sergeant Munro said police weren't anticipating any trouble from this afternoon's game, but they would have patrols around the ground.
