It has generated 43 bookings in the past 10 meetings, and sendings-off for Paul Scholes and Wes Brown, but Manchester United versus Liverpool has been a fixture short of dug-out rancour. Until now. Relations between Sir Alex Ferguson and Rafa Benitez appear to have headed in the Sir Paul McCartney-Heather Mills direction. An entente had existed between the managers, despite the rivalry between their clubs, with Ferguson even sending Benitez a congratulatory letter after the 2005 Champions League final, but feelings have hardened. Notebooks quivered happily in reporters’ hands as, iIn the build-up to this afternoon’s derby, there was the outbreak of a good old-fashioned war of words.

On Wednesday, in his programme notes for United’s home game versus Bolton, Ferguson reiterated his periodic appeal for Cristiano Ronaldo to be given greater protection from bad tackling. In a press conference on Thursday, Benitez accused Ferguson of bringing the matter up in order to begin putting pressure on Steve Bennett, the referee at Old Trafford today. The knight grew dark. On Friday, at his own weekly briefing, Sir Alex hit back. “It’s interesting Rafa Benitez has come out saying I’ve been talking about protecting Ronaldo because we’re playing Liverpool. I’ve been talking about this for two years. I don’t think Rafa can be reading the papers,” Ferguson said.

“All he’s doing, Rafa, is trying to get the referee on his side. That’s exactly what he’s trying to do.I’ve never heard him talking about referees so much. He must think we’re bloody stupid. And you can quote me on that.” Friction first arose between Ferguson and Benitez last summer, when the United manager made sure Gabriel Heinze’s attempt to gain a transfer to Liverpool was blocked. Since Benitez lost Jose Mourinho as a jousting partner and a bit of the fire went out in relations between Ferguson and his old nemesis, Arsène Wenger, two Mr Punches have been missing a Judy. The spat has spiced what would have been a piquant contest in any case with, on top of the fixture’s history, United looking to open a six-point lead over Arsenal in advance of the Gunners’ later kick-off versus Chelsea, and Liverpool fighting Everton for fourth place. Conversation over the post match Rioja in the manager’s room at Old Trafford will be “interesting.’

Liverpool have won their past seven games, Benitez’ arrives at Old Trafford after overseeing seven straight victories whereas preceding United’s win at Anfield in December they , his team had just lost in the league to Reading. Ferguson rejected the idea he was facing a “different Liverpool”.’ “They haven’t changed much,” he said. “They’re strong defensively, as they were back then. “The difference is maybe they have a more consistent team selection,” he said. “It seems to be the same players picked all the time.That’s the only change.” Despite Ferguson’s anger over the refereeing issue, the latter was not delivered in the manner of someone making a jibe, though some might interpret it as one regarding Benitez’s rotation policy. “ It’s unusual you can predict the Liverpool team more easily than the United one, because usually I can’t pick it. Maybe I can this time, but I couldn’t the last time we played them. I find it difficult to pick their team, but I think people find it difficult to pick ours,” Ferguson added.

Ronaldo, no matter how defenders treat him today, must overcome a punishing opponent: precedent - he has never scored against Liverpool or Chelsea. Having scored all the goals in his side’s plast three victories, the Portuguese is certainly in the right fettle. “You can’t deny his form is incredible. You anticipate something will always happen every time he’s on the ball, and he’s still only 23. It helps that he has a warm personality and a good intelligence for the game. He’s able to enjoy being a footballer, knowing it’s a hard business,” Ferguson said.

Though he would prefer if the hype over his No 7 was deflated a little, he did not rebuff comparisons between Ronaldo’s centrality to United’s fortunes this season and what Eric Cantona did en route to the title in 1995-96. “Cantona was important for making and scoring goals at important times for us. Just when you thought you could drop a point, he would make or score one for you,” Ferguson said. “He was without doubt one of the most important players to be here, but Ronaldo is younger and improving all the time. I hope that get him to the highest level and there are signs he’s going that way. Maybe we will look back at the end of this season and say his goals were the most important.”

Bennett does not seem the obvious candidate as a referee for Ferguson to influence. The pair have had their run-ins, notably in the Manchester derby in January, 2006, when Bennett sent Ronaldo off and Wayne Rooney and Ferguson were censured following a row with the official in the tunnel. Invited to talk specifically about Bennett, Ferguson kept his own counsel and even spoke in defence of Wenger, saying his old nemesis deserved to be shown “patience” amid Arsenal’s poor run of league results. He was being peaceable, except when it came to Benitez.