Under the toughest ever guidelines imposed by the English Football Association, fans turning up are banned from the stadium - unless they can prove they genuinely support Turkey.
About 5000 local police, dozens of British and Turkish officers have been on duty to screen airports.
The UK government also issued dire warning to dissuade hundreds of England fans travelling to Istanbul for Saturday's decisive Euro 2004 qualifier match between England and Turkey.
David Swift, head of the English police team in Istanbul, told reporters on Saturday that 43 fans had already been booked on flights back to Britain.
The match between England and Turkey is being played amid unprecedented security over fears of violence between the two sets of fans.
The FA took the unusual step of waiving its share of match tickets and asked for English supporters to be banned from the Sukru Saracoglu stadium. Local police will bar anyone without Turkish ID trying to enter the arena.
Most English fans have stayed away – but a determined minority have resorted to varying degrees of disguise to get past police watching for known troublemakers and obvious football fans.
Dozens English fans have been roaming the city, Turkish television has reported. And UK newspapers have quoted police and members of the infamous English hooligan element saying hundreds of thugs are set on making their presence felt.
Fears of violence are not unfounded. Two supporters of the English club Leeds United were stabbed to death before a UEFA Cup match against Istanbul side Galatasaray in April 2000.
England captain David Beckham
has urged fans to stay away
And when the two national teams met in the English city of Sunderland in April, England's victory was blemished by pre-match violence, two pitch invasions and racist goading of Turkish fans by local supporters.
As a result, European football’s governing body, UEFA, fined England a record £70,000 ($111,000). Moreover, it warned the English FA any repeat would see its team – needing just one point from a draw tonight to qualify – thrown out of the Euro 2004 finals in Portugal.
Turkey has also been cautioned to ensure its supporters - who have a reputation for hostility towards rivals - behave themselves.
Local fans have been told not to jeer at England players during the match. Small items that could be thrown onto the pitch, such as mobile telephones, coins and lighters, as well as umbrellas, bottles, flares and fireworks, are banned.
But tonight’s match is crucial to both sides and therefore an irresistible magnet for die-hard fans that is likely to stir much passion. A victory for Turkey will automatically qualify them for the finals instead of England.