In June 2003, Chelsea announced their biggest 'signing' and it was not a player, but the arrival of Roman Abramovich.
Over the following seasons, bankrolled by the deep pockets of the Russian, the London club roared back to life with a number of marquee signings.
The likes of Didier Drogba, Michael Essien, Hernan Crespo, Michael Ballack, Andry Schevchenko just to name but a few made their way to Stamford Bridge as the Blue juggernaut ruled the Premier League.
The club enjoyed massive success and continued attracting the creme of world football; they could basically sign anyone.
But, even in the finest of plans, something is bound to go wrong, and Chelsea missed out on a number of stars who instead joined rival clubs, and in this case, Manchester City.
The Manchester club replaced Chelsea at the top of the Premier League's spending table thanks to Sheikh Mansour's Abu Dhabi United Group.
They knocked the Blues off the top spot, and made big-name signings, among them three Chelsea targets.
The Brazilian was set for a move to Chelsea back in 2008. All was set for a £32.5m final day deal during the summer window from Real Madrid, but City snatched him from under Luis Filipe Scolari’s nose to make a statement of intent.
He was the first mega-money signing for City and would open the doors for more big-name signings in the following years.
He recently admitted he was set for a move to London until the Spanish side felt infuriated.
“I wanted to go to Chelsea,” Robinho revealed in a recent interview, “Scolari told me that I could make the difference for him in the team.
“However, Real Madrid ended up badly with them, they didn’t like the way that Chelsea sold shirts with my name on them before the deal was done.
“I am sure it was this that led to the negotiations to fail and it was a case of pride for Real Madrid,"
He, however, did not stay at Manchester City for long, leaving half-way through the following season.
🇪🇸 David Silva
Two years after Robinho's miss, the Blues lost another gem, this time, Spanish playmaker David Silva who was at Valencia at the time.
In June 2010, Silva confirmed he wanted to join the London side, saying;
"Chelsea have established themselves as one of the best clubs in Europe over the last five years. There is no reason why in the future Chelsea can’t be as decorated as Real Madrid.
"In players like John Terry, Frank Lampard and Didier Drogba, they have players who would get into any team in the world and it would be a pleasure to play with them.
"There is no doubt in my mind that Chelsea would be a great club to play for – and a club where I could fulfil my ambition of league titles and the European Cup. The Premier League is still the place to be,"
He joined City after the 2010 World Cup, becoming Roberto Mancini's second signing after Jerome Boateng.
He has gone on to attain legendary status, a decade of success that will come to an end at the end of the current campaign.
🇦🇷 Sergio Aguero
Manchester City completed a £38million deal for the Argentine in 2011, and clearly it is one of their best signing in history.
The former Atletico Madrid man has gone on to become a club legend, topping the scorers' charts and continues to terrorize the Premier League.
Chelsea had been keeping tabs on the then 21-year-old, and came close to striking a deal in 2009, but his wage demands were reportedly too high.
AA of Sergio Aguero's second goal vs. Chelsea pic.twitter.com/oa7GcEQd0Y— The Locker Room (@TheLockerRoomHD) April 16, 2016
Then in 2011, Roman Abramovich balked at splashing £40 million for the striker but interestingly paid £50 for Fernando Torres a few months later.
He might be on top of the list of a host of players the Blues missed out on, and many fans wonder what it would have been like to have the striker at the London club.