Rafa Benitez believes that Liverpool are finally ready to defeat their bitterest rivals - thanks to the man he dubs the new Roy Keane.
The Spanish coach has only ever tasted victory over Manchester United once in England.
Peter Crouch's goal in an FA Cup win in 2006 was the only time a Liverpool player has scored against United under Benitez in eight attempts.
But now the Anfield boss believes the psychological hold United clearly have over his team can be released.
AdvertisementAnd it is midfielder Javier Mascherano - a player United tried to sign - who he believes will hold the key in a game that could go a long way to deciding the destination of this season's title.
Benitez sees a lot of Roy Keane in the Argentine, and he stressed his importance to Liverpool when he said: "Javier gives us balance and leadership.
"Like Roy Keane he is a player with a strong character and like him, he could be a very important leader for us in the future.
"What impresses about him is his attitude. He has developed already and when he understands the language even more he will become even more of a leader, which is what we need.
"In terms of winning a game with his attacking actions, that is not Mascherano's role. But in terms of the balance he brings to the side, he is our key player. He gives players like Torres and Gerrard the freedom in attack. That will be important at Manchester United."
United tried to sign Mascherano when his brief tenure at West Ham came to an unhappy end, and Benitez believes he can show them exactly what they are missing tomorrow.
On the pitch he is the quiet organiser and midfield enforcer that Liverpool have lacked in recent years, and United had in Keane during their glory years.
Alex Ferguson has spent almost £60m in trying to replace his former skipper, as he has brought in Michael Carrick, Owen Hargreaves and Anderson.
But Benitez seems to think that he has got the best deal by signing Mascherano for £17million. "We are very happy with Mascherano, and we are very happy with the price we paid for him," he said.
"I don't know how serious Manchester United were about trying to sign Javier.
They have signed two or three players in his position, and they have spent a lot more money than we did.
"We are happy but I don't know if they are happy. All I can say is that he was a good buy for us."
Liverpool go into the game as the form team in England having won their last seven matches, and Benitez believes his side are finally equipped to overcome their biggest rivals.
"We are in a good moment, we have a lot of confidence now and we genuinely believe we can compete with anyone because of the form we are in," he said.
"We have confidence that we can win at Old Trafford. We are in a much better position than in the past.
"We have a stronger squad, we have better players and we have progressed.
They have match winners, it is true, they have fantastic players like Ronaldo, Rooney and Tevez who can create and score.
"But we have that too."
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Tv Times: Live on Sky Sports 1, kick-off 1.30pm