Chelsea boss Jose Mourinho accused Humberside referee Neale Barry of being influenced by United boss Sir Alex Ferguson.
Chelsea drew the first leg of their Carling Cup 0-0 with Manchester United but it left a sour taste in the mouth of the Portuguese man.
“What I thought, felt and saw at half-time, it’s important (for me) to understand a few things.”
He clarified that by saying “When the ref blew the half time whistle he did not walk alone to the dressing room, he should go with his officials, there was someone with him I’ll tell the FA what I saw.
I could not understand it.
“It’s easy then to understand the change of the ref’s performance from the first to second half.
"A big personality was influenced the ref.
“I’m serious about this, but I have to laugh also about it."
Mourinho went on: “One team tried to win, the other side played for a clean sheet and fought a lot, they were very good defensively.
"I accept the result but it was unfair on us," he added.