Chelsea are now closing in on a £45million deal to sign Raheem Sterling, who has spent the last seven years at Manchester City.
We've taken a look at the 14 players Chelsea have previously signed from their 'big six' rivals in the Premier League era, and how they fared at Stamford Bridge.
Olivier Giroud
After falling down the pecking order at Arsenal following Pierre-Emerick Aubameyang's arrival, Giroud swapped red for blue and joined Chelsea in January 2018.
The France international often found himself on the bench but could always be counted upon when called into the team and scored a respectable 39 goals in 119 appearances for the Blues.
Most notably, he got the opener in the 2018 FA Cup semi-final and also came back to haunt Arsenal in the 2019 Europa League final as Chelsea went on to lift both trophies.
The striker also scored six goals during Chelsea's successful Champions League campaign in 2020-21 before departing for AC Milan.
Willy Caballero
Having acted as a backup goalkeeper for Manchester City, Caballero moved to Chelsea on a free transfer in 2017 and took up the exact same role.
The former Argentina international kept 14 clean sheets in 38 appearances in all competitions during his four years at Stamford Bridge but his most memorable moment came when he didn't play.
Maurizio Sarri famously tried to bring him onto the pitch for the final minutes of the 2019 Carabao Cup final against City, only for Kepa Arrizabalaga to refuse to come off.
Raul Meireles
Chelsea failed to sign Luka Modric from Tottenham in 2011 and then turned their attention to Meireles, who had just won the PFA Fans' Player of the Year award during his solitary season at Liverpool.
The midfielder scored six goals in 45 appearances in a debut season which culminated with Champions League and FA Cup winner's medals.
He was then deemed surplus to requirements by Roberto Di Matteo and joined Turkish side Fenerbahce in an £8million deal in September 2012.
Fernando Torres
After developing into one of the best strikers in the world during his three-and-a-half years at Liverpool, Torres completed a £50million move to Chelsea in January 2011.
Admittedly, the former Spain international didn't replicate that Liverpool form at Stamford Bridge but his time at Chelsea wasn't as bad as you might remember.
He also became a Chelsea cult hero by scoring that breakaway goal against Barcelona in the 2012 Champions League semi-final second leg.
Yossi Benayoun
Another player who enjoyed their best Premier League years at Anfield, Benayoun joined Chelsea from Liverpool in the summer of 2010.
The former Israel international didn't get much of a chance to showcase his skills at Stamford Bridge, starting just seven games for the Blues and making a further 17 substitute appearances.
After loan spells at Arsenal and West Ham, he was released at the end of the 2012-13 season and then joined Queens Park Rangers on a free transfer.
Daniel Sturridge
A Manchester Cty academy graduate, Sturridge chose to make the switch to Chelsea when his contract expired at the end of the 2008-09 season.
But the striker found himself behind the likes of Didier Drogba, Nicolas Anelka and Salomon Kalou in the pecking order and couldn't cement a place in the starting XI.
He still scored 24 goals in 96 appearances in all competitions during his three-and-a-half years at the club and had a respectable record of a goal every 188.9 minutes.
Sturridge also picked up a Premier League title, two FA Cups and a Champions League at Stamford Bridge but it was at Liverpool where the striker truly shone.
Ashley Cole
After managing to piss off every single Arsenal fan, Cole left north London and joined Chelsea in a cash-plus William Gallas deal in 2006.
The left-back soon became a Chelsea icon, winning the Premier League, four FA Cups and the Champions League during his eight years with the club.
Shaun Wright-Phillips
While Manchester City are now one of the richest clubs in the world, they were struggling financially in 2005 and couldn't refuse Chelsea's £21million bid for Wright-Phillips.
The winger made 125 appearances for Chelsea but struggled to establish himself in the starting XI due to the form of Arjen Robben and Damien Duff.
He won the Premier League and an FA Cup but was left out of the matchday squad for the 2008 Champions League final and was then allowed to return to City in an £8.5million deal.
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Juan Sebastian Veron
Despite watching Veron struggle with the pace and physicality of the Premier League during his two years at Manchester United, Chelsea still thought he'd be the perfect midfield addition in the summer of 2003.
He scored on his debut at Liverpool but that was as good as it got for the former Argentina international, who made just 15 appearances during his solitary season at Chelsea.
"I felt that going to Chelsea could have been a good chance for me to get a longer sequence of matches, but I shouldn't have gone there," Veron told FourFourTwo in 2021.
"I don't say that because of Chelsea, though. It's nice to have a club wanting to sign you, excited that you can do something for them. To make an investment like that, the club has to believe in you and trust you.
"I actually found it tougher to live in London than Manchester because I'm from La Plata, which is quite a small city. I wish I could have stayed at United longer, as I believe I could have done things differently."
Mark Bosnich
After Bosnich's Manchester United contract was terminated by mutual consent in January 2001, Chelsea ignored the red flags and acted quickly to sign him on a three-and-a-half-year contract.
The goalkeeper, who was once described by Sir Alex Ferguson as a "terrible professional," made just seven appearances for the Blues due to a series of fitness and injury issues.
If that wasn't bad enough, his time at Stamford Bridge ended in infamy as he was sacked and banned for nine months after failing a drugs test.
Mark Hughes
Having won every domestic honour during his two stints with Manchester United, Hughes then joined his boyhood club in a £1.5million deal in 1995.
The striker later formed an iconic partnership with Gianfranco Zola and scored 39 times in 123 appearances, including crucial goals that helped the Blues win the FA Cup, League Cup and UEFA Cup Winners' Cup.
"I had three really good years there, at the start of the modern day times for them. They were beginning to become one of the big teams in the country then," Hughes said.
"I joined with Ruud Gullit and then
Terry Phelan
Signed from Manchester City in November 1995, Phelan made just 15 Premier League appearances for Chelsea and joined Everton a year later after falling out with player-manager Ruud Gullit.
David Rocastle
An Arsenal legend, Rocastle had brief spells with Leeds and Manchester City before returning to London with Chelsea in 1994.
The midfielder scored two goals in 39 appearances in his debut season and his experience proved invaluable as they reached the semi-finals of the UEFA Cup Winners' Cup.
But injury problems restricted him to just one appearance in 1995-96, and he had loan spells at Norwich and Hull before being released in 1998.
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Mal Donaghy
The fourth ex-Manchester United player to appear on this list, Donaghy joined Chelsea shortly before the commencement of the inaugural Premier League campaign.
Despite being 34 when he arrived at Stamford Bridge, the former Northern Ireland international proved to be a key figure in Chelsea's backline and made 78 appearances during his two seasons at the club.
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