Chelsea interim coach Rafael Benitez has risked sparking a fresh war with Alex Ferguson by appearing to question the Manchester United manager's "education".
The pair frequently clashed during Benitez's previous stint at Liverpool and the bad blood was in evidence again during Sunday's 2-2 draw between the sides in the FA Cup quarter-final at Old Trafford.
United led 2-0 through early goals from Javier Hernandez and Wayne Rooney, but the hosts took their foot off the pedal and Chelsea hit back through Eden Hazard and Ramires to force a replay.
After the final whistle, Benitez strode down the touchline towards the tunnel with apparent disregard for the conventional managers' hand-shake that usually follows the end of the game.
However, when asked to explain himself, Benitez suggested he had acted in retaliation after Ferguson blanked him prior to the game.
"I was waiting at the beginning," Benitez told reporters.
"I was in his way and he... (gestures to indicate Ferguson walking past)."
When Benitez was asked why Ferguson had not greeted him, he said: "Ask him. If you are brave enough, ask him. I don't know, it's his decision. I was waiting.
"I have education, because I know a lot of people are watching, so I know what I have to do."
Questioned why he had ignored Ferguson at the end of the game, the Spaniard smiled and said: "I was with my players, celebrating."