Former Manchester United star Gerard Piqué has warned Sir Alex Ferguson that he intends to use the lessons he learned at Old Trafford to break his heart in Rome.

Pique, now a Barcelona defender, believes it is fate that he will score to rob Fergie's team of a trophy Treble.

The 22-year-old Catalan player, who spent four years at Manchester United, said: "I'm going to score, I predict it, and every time this season I've predicted it, it brings us luck.

"I don't want revenge on United because I owe them a lot and I left with tremendous good feeling for the manager and the club. But you can show too much respect in this world and we are here to win irrespective of the gratitude I feel to them.

"Alex was like a second dad to me, not like a football coach. In fact I'd go so far as to say that it was like he was the club owner at United.

"You don't see him on the training ground every day but when he takes you aside and imparts his knowledge or inspires you then you sense his intelligence and what makes him exceptional.

"Under his instruction I learned to be a professional. I learned to push aside distractions, which there are plenty of when you are a young footballer at a big club, and he also taught me how to defend when you don't have the ball near you. When you grow up like me it's important that someone teaches you that height and power aren't everything – you must read the game, use your body to turn a striker and be up for the physical battles.

“So after the experience I gained at United I know how they have prepared to beat us. The training this week will probably have been with Mick Phelan up to the point when the videos have been studied and then Alex will take over. What he says to you sticks with you and his principal points will be the specific things he believes United can do to take adavantage of opportunities he sees in our style of play.

“But I'll try to be a footballing double agent' and let our coach know what we can profit from in the United line-up”.

The headed goal which Piqué scored against Roma last season was one of few in a career at Old Trafford he would have extended if Carlos Queiroz had not been of the opinion that he was not tough enough and couldn't aspire to inherit Rio Ferdinand's mantle.

Part of a rat pack in the United dressing room which included Rio, Rooney, Wes Brown, John O'Shea and Carlos Tevez the centre-half has become the chief jester in the Barça dressing room. He's hoping to have the last laugh tonight when Fergie might wish that Piqué was wearing the red and white of United and not the blue and scarlet of Football Club Barcelona.