Petr Cech brought an end to one of football's worst kept secrets earlier this week when he finalised his move from Chelsea to rivals Arsenal.
The experienced goalkeeper is by no means the first player to have represented both London clubs and with that in mind, Sports Mole has picked out five others that have recently pulled on the red and blue shirts.
1. Ashley Cole
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Very few players have switched between the two clubs directly, but Cole was one that decided to cross the divide in the summer of 2006. Previously idolised by Arsenal fans, the move to Stamford Bridge would forever make him public enemy number one in North London.
Love him or loathe him, what cannot be doubted is that the left-back was a success at both clubs. He won two Premier League titles and three FA Cups after rising through the ranks at Arsenal, before lifting the Premier League trophy one more time with Chelsea. His eight-year stint with the West Londoners also yielded four FA Cups and the Champions League in 2012.
2. William Gallas
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To smooth over the Cole deal, Chelsea allowed Gallas to join Arsenal in part exchange. Yet, while Cole would go on to win numerous honours, the same could not be said of the French centre-back's time with the Gunners.
Playing in an unorthodox left-back position much of the time, Gallas was a member of the Jose Mourinho teams that won back-to-back Premier League titles in the mid-2000s. He was made captain of Arsenal by Arsene Wenger soon after his arrival in 2006, but he was unable to lead the club to glory prior to his departure to fellow North Londoners Tottenham Hotspur on a free transfer in 2010.
3. Emmanuel Petit
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Not too much was known of Petit on English shores when he joined Arsenal from Monaco for £2.5m during the summer of 1997, yet the midfielder made an instant impact. Playing alongside fellow Frenchman Patrick Vieira, the pair spearheaded the Gunners to a Premier League and FA Cup double in his debut season.
He left for Barcelona in the year 2000, but after an unhappy 12 months at the Camp Nou, Petit returned to London with Chelsea. His time with the Blues was not overly successful, with injuries limiting his appearances. However, he was fit enough to play in the 2002 FA Cup final, which saw Chelsea lose 2-0 to his former club.
4. Nicolas Anelka
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A journeyman footballer if ever there was one, it's little surprise that Anelka played for both Arsenal and Chelsea. He joined the Gunners as a 17-year-old from Paris Saint-Germain and despite initially struggling to force his way into the team, an injury to Ian Wright gave the youngster his chance. He made the most of it, scoring important goals as Arsenal won the double in 1998, which earned him a switch to Real Madrid a year later.
Nine years and six clubs later, Anelka arrived at Chelsea in a £15m deal from Bolton Wanderers. He missed the crucial penalty as the Blues lost the 2008 Champions League final in Moscow to Manchester United, but still played his part in one Premier League title and two FA Cup wins.
5. Cesc Fabregas
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Despite being desperate to keep hold of the Spanish playmaker, few Arsenal fans begrudged Fabregas a move back to his native Barcelona in the summer of 2011. Although he only had one FA Cup to show for his time at the Emirates Stadium, Fabregas had served the club with such distinction.
Yet, some of the good feeling towards the midfielder evaporated when he secured a move to Chelsea in 2014, having seen his fairytale return to the Camp Nou go sour. To make matters even worse, Fabregas ended up being a vital cog in Chelsea's Premier League title triumph - a trophy that had always eluded him during his time with Arsenal.
