When Arsenal and Chelsea face each other in the FA Cup final at Wembley on Saturday it will be the latest instalment in a fierce rivalry.
One of the most intriguing aspects of this London rivalry is that, especially in recent years, there have been a significant amount of players who have represented both sides - most notoriously Ashley Cole.
Here, Sportsmail selects the best XI of players who have played for both Arsenal and Chelsea down the years...
Ashley Cole and William Gallas are in the best XI to have played for both Arsenal and Chelsea
Petr Cech: Chelsea 2004-2015, Arsenal 2015-2019
The only goalkeeper to have played for both clubs, Cech spent the majority of his career at Chelsea and won an array of trophies, including the Champions League, four Premier League titles, four FA Cups and three League Cups.
He made the switch to Arsenal in 2015, but, despite some encouraging performances in his first season, he started to decline before eventually retiring in 2019.
Fittingly, the last appearance of Cech's career came for Arsenal against Chelsea in the Europa League final last year, but the Blues prevailed 4-1. Shortly afterwards he returned to Chelsea as a technical advisor.
Petr Cech ended his career at Arsenal but the goalkeeper enjoyed much success at Chelsea
Right back - John Hollins: Chelsea 1963-1975, Arsenal 1979-1983, Chelsea 1983-1984
Hollins was an outstanding midfielder during his illustrious first spell at Chelsea, but fits into this team at right back, where he often featured for Arsenal later in his career.
During his first spell at Chelsea Hollins scored 69 times, while he won the FA Cup, the Cup Winners' Cup and the League Cup.
After moving to Queens Park Rangers, he went on to Arsenal, where he was named the club's player of the year in 1982 prior to returning to Chelsea.
A superb midfielder for Chelsea, John Hollins often featured at right back when at Arsenal
Centre back - David Luiz: Chelsea 2010-2014, 2016-2019, Arsenal 2019-present
Another who had two spells at Chelsea, Luiz has often fluctuated between being hugely impressive and error prone.
Luiz won a wide array of trophies at Chelsea, including the Champions League in 2012 and the Premier League in 2017.
Since joining Arsenal he has already conceded five penalties in the Premier League.
Defender David Luiz is the latest player to have represented both Arsenal and Chelsea
Centre back - William Gallas: Chelsea 2001-2006, Arsenal 2006-2010
A player who doesn't know the meaning of the word loyalty, Gallas achieved the rare feat of playing for Chelsea, Arsenal and Tottenham.
The centre back featured heavily for Chelsea, racking up over 200 appearances, and winning two league titles as well as the League Cup.
Although he had some good performances at times after crossing the divide as part of a move involving Ashley Cole, Gallas' time at Arsenal was less successful, with his most high-profile moment coming when he was stripped of the captaincy.
William Gallas had lengthy spells at both Arsenal and Chelsea during an eventful career
Left back - Ashley Cole: Arsenal 1999-2006, Chelsea 2006-2014
Many Arsenal fans still haven't forgiven Cole for his controversial move to Chelsea, but there is no question that he was a huge success for both clubs.
A key part of Arsenal's invincibles side in 2004, from his perspective Cole was certainly vindicated in joining Chelsea as he went on to enjoy much success there.
Amongst the many other honours he won, Cole lifted the FA Cup on a record seven occasions - four times with Chelsea and three times with Arsenal.
Ashley Cole came through the ranks at Arsenal before making a controversial move to Chelsea
Defender Bill Dickson made over 100 appearances for Chelsea in the league and later played for Arsenal between 1953 and 1956 but didn't win any trophies with either club.
Colin Pates represented both teams