Police are cautioning Western Sydney Wanderers and Central Coast Mariners fans about anti-social behaviour ahead of the hotly-anticipated clash between the leading A-League clubs.A capacity crowd of up to 19,000 fans is expected at Bluetongue Stadium in Gosford on Saturday night for the top-of-the-ladder contest between the leaders and newcomers.About 5000 Wanderers fans will make the journey via public transport or private vehicles.Police issued a warning on Friday saying they'll be cracking down on anti-social behaviour such as lighting of flares or fireworks and alcohol-related violence.A large police presence, including an operational support group, the dog unit and highway patrol officers will be targeting trouble-makers in and around the ground.Those found with flares may be ejected, arrested or face a five-year ban under FFA regulations."Win, lose, or draw, there is no excuse for violent or unruly behaviour," Brisbane Water local area commander superintendent Daniel Sullivan said in a statement on Friday."Anyone seen causing trouble will be arrested and dealt with accordingly."The warning comes months after an incident which resulted in the arrest of a group of Wanderers fans - known as the Red and Black Bloc (RBB) - for lighting flares and smashing chairs.Following the December incident, the RBB lost fan privileges such as the use of megaphones, oversized flags and instruments at games.The privileges were reinstated a week later.A Wanderers spokesman told AAP while the club held a zero-tolerance policy on anti-social behaviour and flare-lighting, it had full confidence in its supporters."Any sort of illegal activity will not be accepted."We have full confidence and faith that the overwhelming majority who attends Bluetongue Stadium on Saturday night will get into the spirit of the supporting their team."We have the best fans and supporters in the A-League and the away attendance is about to set a new benchmark in the league."A spokesman for the Mariners said the safety of all supporters was paramount."If police and security staff believe anti-social behaviour is occurring, then we back their decision to reprimand the minority, not only at tomorrow's game, but in future fixtures and in society."Fans are also cautioned over transport delays with trackwork on the Central Coast line meaning buses will replace trains.Wanderers management have organised extra buses in preparation for travelling crowds.