1. Nick Barmby
Although Abel Xavier has since made the switch, it was Barmby's decision to turn down a new contract with the Toffees and make a £6m move to Anfield in 2000 that was most controversial.
"I want to play for Liverpool," the midfielder declared, which Everton chairman Bill Kenwright described as "six of the worst words in the English language".
2. Johan Cruyff
Aged 36 and with eight Eredivisie, one La Liga and three European Cup titles to his name, Cruyff was already a legend of the game by summer 1983. Yet after helping Ajax to another league and cup double, he was rewarded by being told he was surplus to requirements.
Cruyff sought revenge and did the unthinkable, penning a deal with the Amsterdam club's bitter rivals Feyenoord. To rub salt into wounds, the forward helped his new side to their own domestic double, scoring against Ajax in a 4-1 win along the way and earning himself a fifth Dutch Footballer of the Year title.
3. Luis Enrique
Now manager of Barcelona, Luis Enrique initially made a name for himself with the Catalans' bitter rivals, Real Madrid. The Spain international spent five years at the Santiago Bernabeu, even emphatically celebrating after scoring against Barça in a 5-0 win in 1995.
Yet just 18 months later he was at the Camp Nou, netting his first goal for his new club against los Blancos in Madrid and celebrating just as exuberantly.
"I don't care what these people think," he later said in reference to the home support. Ouch.
- Luis Enrique, One-on-One: "It was easy to join Barça – I honoured my contract at Madrid, I didn’t break it"
4. Sol Campbell
After coming through the Tottenham academy and playing in the first team for nine years, Campbell had secured legendary status at White Hart Lane by the turn of the millennium.
With his contract running down in 2001, the defender allayed the fear of Spurs fans by confirming he would remain in north London; little did they know that would mean their worst nightmare coming true. Campbell completed a free transfer to Arsenal that summer and is still referred to as 'Judas' on the Seven Sisters Road.
5. Michalis Konstantinou
Born in Cyprus, the self-confessed boyhood Panathinaikos fan completed his dream move to the club in 2000 and became a hero when he scored two goals against their great rivals Olympiakos to win the Greek Super Cup three years later.
But a year later Konstantinou had run down his contract and moved to Piraeus, stating: "I'm turning a page in my life and I don’t want to speak about the past."
Inevitably the striker's debut for Olympiakos was against his old side – and after the team bus was bottled into the ground, a banner aimed at the Cypriot was unfurled by his former supporters, which read: "We knew that you were not a man. We did not know that you were a greedy parasite." Olympiakos won 2-0, and went on to scoop a domestic double.
6. Andreas Moller
Moller had been a key player for Borussia Dortmund in their Bundesliga and Champions League triumphs of the 1990s, which is why his move to Schalke on a free in 2000 came as such a shock. Such is the strength of feeling surrounding the Revierderby that many fans of his new club couldn't accept the Dortmund icon following his arrival.
Most of those doubters were converted when Moller helped them to the DFB-Pokal in his first season, though, while the Royal Blues were also just a whisker away from their first league title since 1958.
7. Alan Smith
When Leeds were relegated from the Premier League in 2004, local lad Smith was carried from the pitch in tears. Supporters knew that the striker would have to be sold for financial reasons, but they found it difficult to take when he rocked up at Old Trafford a few weeks later.
Smith won the Premier League title with Manchester United in 2007, but struggled to hold down a first-team place throughout his time at Old Trafford. "I was young and naive," Smith later told FFT when asked about the time he insisted he'd never play for the Red Devils. Oops.
8. Haim Revivo
When Fenerbahce won the last ever 1.Lig (before it became the Super Lig) title in 2001 and denied fierce rivals Galatasaray their fifth successive championship, their top scorer with 14 goals was midfielder Revivo. The Jewish-Israeli was regarded as one of Fener's own by the club's fans – until he made the move across Istanbul to Galatasaray, that is.
Love turned to hate at the Sukru Sarakoglu soon after, as Revivo was signed as a successor to Gheorghe Hagi. Although he would go on to struggle during his sole season at the club, the damage had already been done.
9. Luis Figo
Controversial transfers work both ways when it comes to Spain's famous rivalry, and none come much bigger than Figo's then-world record £37.2m move from Barcelona to Madrid.
A Barça favourite for his performances over the previous five years, the Portuguese winger was signed as Florentino Perez's first Galactico in summer 2000. Angry Catalonians responded by launching a severed pig's head in his direction during a Camp Nou Clasico two years later.
10. Carlos Tevez
Five years after the Smith saga, the Red Devils would get a taste of their own medicine when Tevez joined their increasingly powerful rivals, Manchester City.
Technically this wasn't a transfer between the two Manchester clubs – the Argentine had just spent two years on loan at United (from West Ham/the two companies that owned the player's rights at the time) – but Alex Ferguson wanted to make the deal permanent before he joined City in 2009.
Despite United having agree to meet the £25.5m option fee, Tevez spurned their advances. City swooped, got their man and to make matters worse, sanctioned a billboard in Deansgate picturing the striker alongside the words 'Welcome to Manchester'. A furious Ferguson dubbed them a "small club with a small mentality".
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