#3 Arjen Robben
At the age of 20, Arjen Robben began to attract attention from big football clubs after eye catching performances for PSV Eindhoven. He scored 21 goals and made 21 assists in 75 appearances for the club.
During the summer of 2004, Sir Alex Ferguson tried to bring the winger to Manchester United.
According to 90min Football, Robben spent an evening having dinner with Ferguson in Manchester. He was also given a tour around the United training complex. However, once Robben returned to PSV, there was no further contact from United, so he decided to take Chelsea's offer and made the switch to London.
The Dutch talisman went on to have a glorious career. After Chelsea, he moved to Real Madrid and later Bayern Munich. He won two Premier League titles, one La Liga title, eight Bundesliga titles and a Champions League title.
#2 Toni Kroos
Towards the end of the 2013-14 season, Toni Kroos was looking for a move away from Bayern Munich, desiring a change in his career. After an abysmal start to his first season at Manchester United, David Moyes decided to pursue the signing of Kroos.
According to Bleacher Report, Kroos revealed that Moyes personally met him and the pair went on to virtually agree a contract. However, Moyes' season went from bad to worse, and he was eventually let go by United. Moyes' successor Louis Van Gaal was not interested in signing the German midfielder, therefore the move failed to go through.
Kroos ended up signing for Real Madrid in 2014 after winning the FIFA World Cup with Germany. He is still enjoying a fabulous career with the Galacticos, accumulating two La Liga titles and three Champions League titles.
#1 Ronaldinho
Ronaldinho was perhaps the biggest one that got away. United manager Sir Alex Ferguson was a big fan of the Brazilian playmaker and did everything he could to bring him to Old Trafford in the summer of 2003.
In an article on the official Manchester United website, Paul Scholes said that the signing of Ronaldinho was almost announced. He was almost assigned a squad number as well.
However, Ronaldinho himself revealed that the President of FC Barcelona did enough to convince him to change his mind. He convinced him at the last minute to join the Catalan giants from PSG.
It goes without saying that he made a fantastic decision, winning the Ballon d'Or and multiple La Liga titles with Barcelona. Missing out on Ronaldinho prompted United to sign young Portuguese winger Cristiano Ronaldo, and the rest is history.