Galatasaray and Besiktas fans could renew their long-running feud on the streets of London when the sides rivals face Arsenal and Tottenham respectively this week.
The Turkish heavyweights have fought violent brawls in the streets and in the stands over bragging rights across Istanbul.
Video footage caught rivals in a street fight earlier this year, while players were forced to flee the pitch during a derby match in September 2013, when hundreds of hardcore ultras invaded the pitch and started throwing chairs.
Almost 6,000 travelling Turkish fans are expected to arrive in London this week when Galatasaray take on Arsenal in the Champions League on Wednesday, with Besiktas facing Tottenham just 24 hours later in the Europa League.
Both matches are being played a stone's throw from the north London heartland of London's Turkish community.
But the Metropolitan Police has told the Daily Mail it is prepared for any potential flash points.
"We are aware of the background of the two clubs and appropriate plans will be in place. We are also aware that the clubs will have supporters already based in London," a spokesman said.
A spokesman for British Transport Police added: "We are used to dealing with large numbers of fans and we are liaising with the clubs to make sure everyone is safe and on the move."
North London fared badly last season when travelling Napoli fans smashed their way through bars and restaurants near Arsenal's Emirates stadium.
Gunners fans were left bloodied and eateries including Piebury Corner had their windows smashed ahead of the Italians' Champions League match against the Premier League club.