The Blues saw the error of their ways in 2014 when they shelled out £21m (Dh102m) to bring the Serbian midfielder back to Stamford Bridge.
GRAEME LE SAUX (CHELSEA)
Sold by Chelsea to Blackburn for just £700,000 (Dh3.4m) after throwing his shirt at manager Ian Porterfield in protest at being substituted. Le Saux became the most expensive defender in England when the Blues forked out £5m (Dh24m) to bring him back.
DANI CARVAJAL (REAL MADRID)
The right-back had not made a single first-team appearance for Real Madrid when they sold him to Bayer Leverkusen for €5m (Dh20m).
However, the canny Spaniards inserted a buy-back clause just in case he turned out to be any good. Which he did. Carvajal returned a season later for €6.5m (Dh26m).
BOBBY ZAMORA (WEST HAM)
Joined West Ham as an apprentice but was released at 17 along with Paul Konchesky. Five years later the relegated Hammers brought Zamora back as part of a deal which saw Jermain Defoe sold to Tottenham.
Played in the 2006 FA Cup final – alongside Konchesky, who cost £1.5m (Dh7m) from Charlton.
ALAN SHEARER (NEWCASTLE UNITED)
Newcastle had a young Shearer growing up on their doorstep and offered him a trial. However, the story goes that they put him in goal. Southampton had the foresight to play Shearer up front and signed the future England captain.
When Newcastle finally got their man it cost a then world-record £15m (Dh72m).
The Blaugrana have allowed another fullback to leave in this transfer window as the 31-year-old Adriano follows Dani Alves out the door.
The Brazil international’s signature is a major boost for the Turkish club’s Champions League aspirations.
Brad Guzan, Aston Villa to Middlesbrough, free (Done Deal)
Boro-bound: Brad Guzan.
The 31-year-old USA international has signed a two-year deal and is likely to provide back-up at Premier League newboys Boro to former Barcelona and Spain stopper Victor Valdes, who joined earlier this summer.
Guzan made 34 appearances for relegated Villa last term.
Andre Ayew, Swansea to West Ham, €19 million (In Talks)
The Hammers have enquired about the availability of the Swansea striker.
Ayew attracted interest from West Ham last summer, but joined the Swans on a free transfer and went on to score 12 goals during his debut season in the Premier League.
Understand NO bid from West Ham or anyone else for Andre Ayew - a @SwansOfficial source says he's an important part of their plans.
The curious case of Ciro. The Italy striker is on the move again.
After earning a big money switch to Borussia Dortmund in 2014, he has since stagnated, joining Sevilla last year before being shipped out on loan to Torino.
He arrives at Lazio looking to resurrect his career.
Alexandre Pato, Corinthians to Villarreal, €3 million (Done Deal)
Pato was a flop at Chelsea last season.
His loan spell at Stamford Bridge did little for the 26-year-old but he has been given another chance to prove his worth in European football with Villarreal, who have reportedly bought 60 per cent of his economic rights.
Ayoze Perez, Newcastle to Barcelona, €17 million (Reported)
The transfer circus has churned out a new name to be linked with Barcelona.
The Spanish forward has reportedly been sounded out with the La Liga giants set to lose out on Atletico Madrid’s Luciano Vietto who is close to making a move to Sevilla.
Mario Balotelli, Liverpool to Besiktas, €6 million (Reported)
Treading water: Mario Balotelli.
It seems Super Mario isn’t quite so super because no side wants to take him from Liverpool.
Boss Jurgen Klopp has made it clear he’s no longer wanted at Anfield but Turkish club Besiktas may come to his aid with club president Fikret Orman a fan.