Manchester United against Real Madrid.It is the game that changed football, between two managers who have certainly changed football, featuring the player Sir Alex Ferguson has been saddest to see leave in his 26 years at Old Trafford.It was a meeting between United and Madrid, a sizzling seven-goal encounter in 2003, that persuaded Roman  Abramovich, who was a guest that night, to buy a football club and so transform the financial landscape of the European game.It was Ferguson who rewrote the modern management manual and Mourinho who then added a couple of new chapters. Mourinho calls Ferguson ‘the boss’.Ferguson says — the Special One’s good looks aside — they boast the same qualities. And then there’s Cristiano Ronaldo.The world’s most expensive player and, alongside Lionel Messi, the world’s finest. In Ferguson’s mind everyone leaves United when the time is right. Either when he says so or when they choose to retire. But Ronaldo was different.Ronaldo was the best he’s ever had — someone who even managed to alter Gary Neville’s view on how the game should be played — and he left before he had even peaked.On March 5 Ronaldo will return to Old Trafford for the first time since his £80million transfer to Madrid in 2009. ‘It’s the tie of the round,’ said Ferguson yesterday.‘It’s a great opportunity for our fans to see Cristiano again and also meet up with Jose — I’ll need to order some good wine.’It is the game. The game that offers so much and evokes so many memories, too.In 2000, Real Madrid beat United 3-2 at Old Trafford thanks to a masterful peformance by the Argentina midfielder Redondo.Then there was the clash in 2003 when the other Ronaldo, the Brazil striker, scored a hat-trick at Old Trafford which convinced Abramovich to pay £140million for a football club.There is also the electrifying image of Mourinho storming down the touchline at Old Trafford in 2004 when Francisco Costinha’s last-minute equaliser for Porto knocked United out of the  Champions League.This time United and Real clash at the Bernabeu on February 13 and then play at Old Trafford on March 5, three days after Real host Barcelona in La Liga’s El Clasico.It is the European Cup or nothing for Mourinho now after Real slipped to defeats against Getafe, Sevilla and Betis in La Liga. Real’s defence of their title is faltering after falling a staggering 13 points behind  Barcelona just 16 games into  the season.