Fulham boss Martin Jol admits concerns over Dimitar Berbatov's body language.

Former Manchester United striker Berbatov is hardly all smiles at the best of times, and with Fulham's form dipping in recent weeks, the sulks and signs of frustration have become more obvious.

"When things were going well, we were happy with him, but when things are not going well, he could be unhappy," said Jol on the eve of a vital festive programme.

"He's almost used to winning games with the clubs where he was [Tottenham and Man United], so we have to talk to him and players have talk to him, and he has to do the same.

"He's got to put in the same sort of attitude or work-rate that he always did. When he does that, there's no problem, but he is certainly a player we have to keep on his toes to do well for us."

Jol added: "We were very happy with him the first couple of months and now he should be happy with us as well, so we have to keep each other happy."