When, in February 2004, Chelsea announced the arrival of Petr Cech, many expected the then 21 year-old to be Carlo Cudicini's long-term - rather than immediate - successor. Like when Thibaut Courtois last season displaced Cech as Chelsea's number one, Cech's inclusion in José Mourinho's first competitive game in charge of the West London outfit saw one of the Premier League's - if not the world's - outstanding goalkeepers being ousted by absolute raw potential. Even with his reputation inflated by a series of stellar showings in Euro 2004 for his native Czech Republic, it seemed highly likely that Cech would be heading to Stamford Bridge to be Cudicini's understudy as, in the summer of 2004, Roman Abramovich's Chelsea project identified a number of potential future greats of the game in Cech, Arjen Robben and Didier Drogba. Instead, not only did Cech establish himself as - statistically - the best goalkeeper in world football in his début season, but he played a pivotal role in a side that secured Chelsea's first league title in fifty years, as well a League Cup triumph at the expense of Liverpool. Going a then record 1,025 minutes unbeaten and then keeping twenty-five clean sheets in the Premier League alone, Cech conceded only fourteen times in 37 league appearances in his first season for the Blues. He only added to his burgeoning status as a goalkeeping great by once again being the most consistent of Mourinho's squad of superstars in the 2005/06 season, as Chelsea once more secured the league crown at a canter. Yet it was in the 2006/07 season that Cech's legend was written. It was in a royal scrap of a game at newly-promoted Reading when Cech was knocked unconscious in a collision with Stephen Hunt. After a similar, but thankfully not as serious collision between Hugo Lloris of Tottenham and Everton's Romelu Lukaku, Mourinho recalled the incident: ‘Petr Cech was dying on the pitch, clearly', said Mourinho. ‘We all know at that moment that he was dying. So there is no space for doubt, no space for question marks, no space for communication or lack of communication between player, doc, manager. There was no space'. Cech suffered a depressed fracture of the skull, which nearly cost him his life. Instead, he returned and in March 2007, after a run of going 810 minutes without conceding since his comeback game against Liverpool, he became the first goalkeeper since Tim Flowers in September 2000 to win the Premier League's Player of the Month award. In his Chelsea career, Cech has won four Premier League titles (2004/05, 2005/06, 2009/10, 2014/15), three League Cups (2004/05, 2006/07, 2014/15), four FA Cups (2006/07, 2008/09, 2009/10, 2011/12), two FA Community Shields (2005/06, 2009/10), one Europa League title (2012/13) and - most significantly in 2011/12 - the UEFA Champions League. That fateful night in Munich remains the greatest night in Chelsea history, and surely in Cech's own illustrious career. Though he was only truly tested once in normal time, as he diverted Robben's drive onto the bar, the giant Czech pulled off a crucial penalty save in extra time from the same player. 'Written in the stars', claimed Gary Neville, as Cech showed almost machine-like focus and application in the resulting penalty shoot-out to deny both Ivica Olic and Bastian Schweinsteiger to win Chelsea the big-eared trophy. Cech showed good grace when he was overthrown by Thibaut Courtois. Recognising that his time had at Chelsea had come full circle, the Czech today posted an open letter to Chelsea fans confirming both his move to Arsenal and the reasons for it. Claiming that he is not yet ready to accept being a number two, Cech explained that he agreed to remain at the club last season to see if his position would change after Mourinho gave Courtois the coveted starting berth. With circumstances still in the Belgian's favour, Cech has agreed on the best move for his family and has decided to remain in the capital for the benefit of his wife and children. For that, no level-headed Chelsea fan could begrudge such a wonderful servant to the club a move to any club, even if it is to one who could end up being deadly rivals for the Premier League title next term. Nevertheless, Cech has shown great respect to the club and the fans, particularly in the past twelve months in remaining at the club despite his relatively untenable position. Cech has been open and honest about his intentions - unlike some - and for that reason he deserved every ounce of gratitude from Chelsea fans around the world. 228 clean sheets, 486 appearances, hundreds of spectacular saves and countless magical moments. Thank you, Petr Cech. Click here to view the article