Chelsea have been accused of being 'pathetic' bad losers following their CL defeat by Barca - and are set to face further embarrassment if UEFA throw out a claim that the Spanish club's coach Frank Rijkaard entered referee Anders Frisk's dressing room at half-time.
The Premiership leaders allege the Barca boss was spotted leaving the room used by the Swedish official.
UEFA have already said that their own tunnel representative witnessed nothing out of the ordinary during the half-time break and it is the Londoners who are likely to be on the receiving end of any punishment after failing to turn-up for the compulsory press conference after their 2-1 defeat.
The referee is not expected to include any of the alleged incidents in his report to UEFA - making Chelsea's case look wafer thin.
Barcelona assistant coach Henk Ten Cate has branded Chelsea's expected complaint to UEFA'pathetic'.
Ten Cate is also angry about a trick played by Chelsea boss Jose Mourinho before kick-off.
Mourinho predicted both starting line-ups, and left Damien Duff out insisting he was injured - but Duff played.
Ten Cate said: 'To react the way Chelsea have is pathetic. Mourinho lied with the line-ups - and now this.'
UEFA spokesman William Gaillard said:'Anders Frisk says Rijkaard greeted him and apologised he had not had the opportunity to say hello before the game.
'We had two UEFA officials there and neither witnessed it. The referee's dressing room was locked and he and his assistants were the only people allowed in.'
UEFA delegate Thomas Giordano added: 'The only unusual thing that happened as far as we are concerned is that Chelsea failed to present themselves in the press conference.
'Nothing abnormal happened at half-time - the coach of Barcelona said hello to the referee, which seems to us an act of someone who is polite and well-educated.'
Frisk was backed by UEFA's head of referees Jermund Nilsson, who said:'If the referee's observer thought something was wrong he would have said so. I am assured that Frisk did nothing wrong and from what I understand Chelsea have very definitely over reacted.'