The feud between Manchester United boss Sir Alex Ferguson and Newcastle United's Alan Pardew was lit immediately after the midweek clash at Old Trafford.
The Sunday Mirror says hostility commenced straight after the final whistle of Manchester United's controversial 4-3 win.
The rival managers exchanged a frosty handshake at full-time but did not have their customary drink together in Ferguson's room. Pardew, a long-standing admirer of his Old Trafford counterpart, has admitted that in the past he has sought out Ferguson's advice, including whether to take the Newcastle job.
The fact they avoided each other after the game - especially at Christmas - points to the tension between the duo following Mike Dean's decision to allow Jonny Evans' disputed own goal.
That impression is heightened by the fact that other members of the Newcastle coaching staff did accept an invitation from Ferguson to have a drink.
Newcastle goalkeeping coach Andy Woodman revealed on Twitter that the Scot had never mentioned problems arising from the game.
Woodman wrote: "Funny! After the game Mr Ferguson offered us a drink and pie! Never said a word to our faces!"