Police warn fans to behave in opening Origin clash in Sydney

Footy fans in Sydney for the State of Origin series opener have been warned to keep the interstate rivalry on the field.

Police have promised to turn out in force as Blues and Maroons fans descend on ANZ Stadium on Wednesday night, targeting anti-social behaviour and booze-fuelled crime.

"Anyone who chooses to engage in criminal, anti-social or unsafe behaviour will be identified and dealt with swiftly," NSW Police Assistant Commissioner Frank Mennilli said.

"Anyone caught causing trouble for others will be removed from the crowd and you may very well face further police action, or be banned from ANZ Stadium."

Punters have been reminded that their game tickets also give them free travel on public transport to and from the match.