#3 Lionel Messi to Manchester City
Manchester City had the opportunity to sign two of the greatest footballers in history this summer but somehow fell short in both cases. A few weeks before the Cristiano Ronaldo saga, an opportunity opened up for the Cityzens to prise Lionel Messi away from Barcelona.
City boss Pep Guardiola expected the Argentine to remain at Camp Nou, so he wasn't thinking about it. However, Barcelona couldn't tie Messi down to a new deal due to their financial troubles and had to let go of the attacker.
Paris Saint-Germain took advantage of the situation and quickly convinced the 6-time Ballon d'Or winner to sign a two-year contract with them. Thanks to the influence of Leo's best friend Neymar, things developed at the speed of light, giving Manchester City their first big blow of the summer.
#2 Diego Maradona to Sheffield United
In one of the most unfortunate misses in football history, Sheffield United let the opportunity to sign the greatest footballer in history pass them by. They could have signed Diego Maradona for almost nothing but they regrettably refused to do so.
Then manager Harry Haslam went on a scouting exercise in Argentina when he noticed the incredible talent of a 17-year-old Maradona. The tactician immediately began preparations for a £200,000 bid for the player but Sheffield's board opted against it. Instead, they signed another Argentine, Alejandro Sabella, for £160,000.
Maradona would later move on to make history with the likes of Boca Juniors, Barcelona and Napoli. He's regarded by many as the greatest player in football history.
#1 Alfredo Di Stefano to Barcelona
Alfredo Di Stefano is well-known as one of the greatest players in Real Madrid history, but many are not aware of just how close he got to joining Barcelona. Even that sounds like an understatement as the Blaugrana actually signed the Argentine in 1953.
The Catalan giants reached an agreement with River Plate, who owned the player's rights. However, Real Madrid also struck a deal with Millionarios, the club the striker was playing for at the time of the deal.
Amid the confusion, it was ruled that the Argentine would play alternate seasons at the two clubs. Angered by the proceedings, Barcelona decided to pull out of the deal, allowing the player to join their rivals.
Di Stefano enjoyed a successful spell at the Santiago Bernabeu. The attacker helped Los Blancos dominate European football, leading them to claim five successive European Cups between 1956 and 1960.