Chelsea boss Jose Mourinho wants an apology from the assistant-referee who ruled out an effort from Salomon Kalou during Saturday's goalless draw with Blackburn Rovers.
The Ivory Coast striker appeared to side-foot home a second-half chance, but the assistant claimed he was offside in the build-up to the 57th minute incident.
Referee Howard Webb ruled out the effort and Mourinho could face disciplinary action after berating fourth official Peter Walton on the touchline.
"I can't understand it. If the linesman wants to explain, then maybe it would be a good thing," said Mourinho.
"I told the linesman I would be waiting for his phone call to apologise.
"We scored a great goal. Only the linesman can tell us why he disallowed the goal."
On the performance, he added: "We lost two points in a performance where I have only good things to say about my players.
"A team without big ammunition, without the two target strikers, Didier (Drogba) and (Claudio) Pizarro plus without a top scorer like (Frank) Lampard.
"The team played well against a good team that fought a lot to keep the clean sheet and go home with a point."