West Ham have taken the unusual step of banning half-and-half scarves for Saturday evening's London derby with Tottenham.
The move is among a number of increased security measures aimed at preventing away supporters from getting into the home sections at the London Stadium for a potentially volatile match.
"Half-and-half scarves or items illustrating the colours/crests of both clubs will not be permitted inside London Stadium on Saturday," a club statement said.
"Supporters who have purchased half-and-half scarves from unofficial sellers will be required to hand them over to security staff at the security checkpoints and these scarves will not be returned."
Niclas Fullkrug is an injury doubt for the hosts.
The 32-year-old striker, who missed a chunk of last season through injury, suffered a calf problem while on international duty with Germany.
"Niclas has had a slight issue with his calf on international duty and came back early," said manager Graham Potter. "He's trained lightly today, but we’ll see how he reacts."
Should Fullkrug miss out then free summer signing Callum Wilson, who scored as a substitute in the 3-0 win at Nottingham Forest a fortnight ago, could make his first Hammers start.
"He’s been great, as we expected. He’s a fantastic professional," added Potter.
"We’re still building him up because he arrived late, but he was great against Nottingham Forest and he’s going to continue to contribute to the team."
