Police issued a warning to football fans as the match between Sunderland and Celtic at the Stadium of Light got underway.
The match began at 3pm in a a pre-season friendly celebrating both 20 years since the Stadium of Light first opened its doors and 50 years since Celtic won the European Cup.
Northumbria Police said it is proud of the "fantastic reputation we have for policing football" in the North East, which it said was "one of the most passionate places in the country when it comes to sport and that is something we want to celebrate".
But the force said it would come down hard on anyone causing trouble at the match or after the game, and warned fans to behave.
A spokesman said: "We will not tolerate disorder inside or outside the stadium and we will have a highly visible policing presence at the Stadium of Light and surrounding cities."
He added: "Police action will be taken against those disturbing the peace and threatening the safety of themselves and others.
"Disorder at our football matches has fallen in recent years and we trust fans to work together with police and the football clubs to maintain this.
"Metros and trains have already been extremely busy for fans arriving to the Stadium of Light and fans are advised to take care when travelling home from the match as well.
"Our priority is the safety of the public, we will be speaking with fans and will be available to offer any advice or reassurance they need."