Portsmouth v Southampton: Derby gets 'largest' football policing in Hampshire
Officers are preparing for their "largest ever football policing operation in Hampshire" ahead of the Portsmouth v Southampton derby.
The clubs will meet in Portsmouth for their Carabao Cup tie on Tuesday, the first time they have played each other since 2012.
Riot police, police dogs, helicopters, horses and drones will be deployed.
Hampshire Constabulary said the police presence was needed to stop a "small minority ruining it for everyone".
The force added it will "quickly act to stop any disruption".
Assistant chief constable Scott Chilton said: "Our priority is public safety and our message is clear - any disorder will not be tolerated."
He added: "We want this match to be remembered for what happens on the pitch, not off it."
Earlier this month, police confirmed Southampton fans will not be escorted to and from Portsmouth's ground, Fratton Park, in a "coach bubble", as they did in 2012 to prevent rival fans meeting.
On that occasion five fans were arrested and six were removed from the stadium.
Southampton FC said fans travelling to the game in club shirts should be wary, and warned any fans bringing the club into disrepute would be "investigated appropriately".