Dimitri Payet is in contract talks with West Ham United, despite signing a five-year deal with the Hammers in the summer.
The club have denied media reports the French 28-year-old midfielder has made demands over a new contract.
A statement said productive talks about a contract improvement and extension have started because of his “outstanding impact”.
Payet has scored six goals in 22 appearances this season.
He joined from French side Marseille in a deal worth more than £10m and has helped the Hammers to sixth in the Premier League.
He tweeted: “I say and I repeat I’m proud to wear the shirt of West Ham. My future is here and I hope for many years.”