Every now and again – but not often – a player will make the brave decision to move from his current club to their biggest rivals.
Becoming an enemy in one community usually sees them become more of a hero in their new surroundings, but there is frequently more drama than meets the eye.
From pigs heads, controversial billboards and surprise press conferences, these deals can bring out the best and worst in football and its fans.
Here, Sportsmail takes a look at 10 transfers between rival clubs that have caused plenty of drama over the years.
Carlos Tevez made the bold decision to move from Manchester United to rivals City in 2009
Manchester City produced a targeted dig at their rivals after signing one of their star players
Carlos Tevez (Manchester United to Manchester City, 2009)
Tevez was always a colourful character on the pitch with his bullish style of play, whacky celebrations and at times his unhinged temper. However, his transfer between the two Manchester clubs was possibly the most bold and daring move of his career.
At the time, City had a huge influx of cash due to the Abu Dhabi takeover 12 months earlier, and they quickly became title challengers, posing a very different threat to United – who had been dominant for so many years.
Sir Alex Ferguson famously branded them ‘noisy neighbours’ – and the signing of the Argentine did little else but raise the volume.
As if taking one of their star players wasn’t enough to give City a smug face, they erected a billboard in Manchester city centre that simply read: ‘Welcome to Manchester’ to announce Tevez’s signing.
The Argentine was prolific during his time at the Etihad Stadium and helped the club win their first ever Premier League title in 2012, despite going AWOL for half of the season after a fall-out with boss Roberto Mancini.
Robert Lewandowski (Borussia Dortmund to Bayern Munich, 2014)
Robert Lewandowski moved from Borussia Dortmund to Bayern Munich in 2014 on a free
The Polish striker enjoyed a very successful time under now-Liverpool manager Jurgen Klopp at Dortmund from 2010 to 2014.
After a league and cup double, finishing as runners-up in the Champions League and then becoming the top goalscorer in the Bundesliga, Lewandowski was hot property, to say the least.
Incredibly, Bayern Munich stole their main rivals’ best player on a free transfer in some of the best business they are ever likely to do.
Since poaching the striker, Lewandowski has netted 153 goals in 182 appearances for Bayern, leading them to five straight Bundesliga titles.
Luis Figo (Barcelona to Real Madrid, 2000)
Luis Figo made a hugely controversial transfer from Barcelona to Real Madrid for £37million
Barcelona fans threw a pig’s head at Figo and the match was halted for 13 minutes due to abuse
Betrayal, a pig’s head and a world record fee – Figo’s move didn’t just shake up LaLiga, but the world of football.
The Portuguese playmaker was widely renowned as one of the world’s greatest players and his arrival at the Bernabeu was marked as the beginning of the ‘Galacticos era’.
He joined for a world record fee of £37million and later that year won the Ballon d’Or – certifying the money spent.
The first meeting back between Figo and the Barcelona fans was not a pretty one.
He was subject to constant, vile abuse at the Nou Camp and the match had to be halted for 13 minutes as a fan threw a pig’s head at him while he was taking a corner.
As Figo joined, so did Zinedine Zidane, Claude Makelele and Ronaldo, and Madrid’s dominance was clear to see with successes in LaLiga, Champions League and UEFA Super Cup. Figo remained an influential figure before leaving for Inter Milan in 2005.
Sol Campbell (Tottenham to Arsenal, 2001)
Sol Campbell became public enemy No 1 when he swapped Tottenham for Arsenal in 2001
Spurs supporters greeted Campbell with ‘Judas’ signs on his return in an Arsenal shirt
This transfer bitterly divided north London. Sol Campbell became one of the highest paid players in the game by moving from Spurs to Arsenal in 2001, but what made the move so extraordinary was the surprise of it all.
Journalists had travelled to Arsenal’s Colney base believing they were witnessing the announcement of Ipswich Town goalkeeper Richard Wright, but instead came out the star defender from the club’s biggest rivals.
The England international caused such an uproar with the shock of this move, he was labelled a ‘Judas’ by the Tottenham faithful. Running up to the move, the defender did state that he would remain in north London, not indulging where exactly, which many believe was very clever PR.
Campbell stayed with Arsenal until 2006 before joining Portsmouth after scoring in the Champions League final. He returned for a short spell in the second half of the 2009-10 season.
Roberto Baggio (Juventus to AC Milan, 1995)
Roberto Baggio left Juventus after five years with the club as he was no longer priority to them
Roberto Baggio was a fine servant for Juventus during his five-year spell at the club and won a Serie A and Coppa Italia double at the end of his final season.
Despite Baggio’s impressive return of 115 goals in 200 matches for the club, they opted to put their focus on exciting talent Alessandro Del Piero, leaving Baggio to find a new club.
Unlike other transfers on the list, that came from a player’s intent to leave, the Divine Ponytail wished to remain at Juventus and fans protested the decision to allow him to go.
The striker joined Fabio Capello’s AC Milan for £6.8m and while he never quite hit the heights of his former years in that team, he still helped them win Serie A in his debut season.
Johan Cruyff (Ajax to Feyenoord, 1983)
Johan Cruyff was so angry at not getting a new contract with Ajax he moved to their rivals
Johan Cruyff, widely regarded as one of the most skilful players to ever play football and well-known for inventing the ‘Cruyff Turn’, indeed has a skeleton inside his closet.
After a successful second spell at Ajax, the club he led to domestic and European glory on several occasions, he was not offered a contract at 36 years old.
Incredibly vexed with the decision, he opted to move to their main rivals out of spite.
While he was past his best by this stage, it was quite the signing for Feyenoord, who had been under-performing for the last 10 or so seasons.
He helped them to their first title in over a decade, a KNVB Cup, and was awarded Dutch Player of the Year. Despite this dispute late in his career, Ajax still chose to name their stadium after him following his death in 2016.
Nick Barmby (Everton to Liverpool, 2000)
Nick Barmby made the fateful Merseyside switch from Everton to Liverpool for £6m in 2000
It’s one thing to move from your current club to their biggest rivals, but to express your desire to move to them before a deal has been made is bold – or, just plain crazy.
In 2000, despite interest from Manchester United, Everton midfielder Nick Barmby made the fateful Merseyside switch to Liverpool for £6m.
Barmby took no time to show Everton what they were missing, too.
He scored in a 3-1 win against his former club in his first season with the Reds as he went on to lift an infamous treble at the end of the season.
Andrea Pirlo (AC Milan to Juventus, 2011)
Andrea Pirlo left AC Milan for Juventus after 10 seasons with the club and continued to shine
Andrea Pirlo established himself as one of the most relaxed, reliable midfielders in world football throughout his career.
He was often praised for his vision, positioning and ability to work in tight spaces.
However, at the peak of his career, AC Milan crazily decided they no longer needed him after 10 years at the club and let him leave for free.
Even at 32 years old, Pirlo was a magician with the ball and for Juventus to snap him up on a free from their biggest rivals would prove quite the chess move in years to come.
He joined under Antonio Conte’s reign and grabbed 13 assists as the club won the league unbeaten in his first campaign.
They went on to win four straight Serie A titles, with Pirlo proving he still had it week in, week out as the anchor of their midfield.
Ashley Cole (Arsenal to Chelsea, 2006)
Ashley Cole was part of a player-swap deal for William Gallas as he joined Chelsea in 2006
Ashley Cole was part of one of the most dramatic and strange transfers in Premier League history.
After a hugely successful time with Arsenal, a part of their famed Invincibles team, Cole moved to bitter rivals Chelsea in a player-swap deal for William Gallas.
He became truly hated by Arsenal fans after it was later revealed that the Gunners had offered him £55,000-a-week to remain at the club.
However, their resentful heckles did not stop Cole becoming a success just a few tube stops away in west London.
He stayed at Stamford Bridge for eight seasons, winning a Premier League title and the Champions League in 2012 before moving to AS Roma in 2014.
Robin van Persie (Arsenal to Manchester United, 2012)
Robin van Persie joined Manchester United and became hated by the Arsenal fans for it
Up to this point, Arsenal had sold some of their best talents potentially a little prematurely but were not willing to meet the player’s demands on how the club should be run, so yet again, listed a star for transfer.
Robin van Persie had been a huge figure in the Arsenal squad, taking over from Thierry Henry as the club’s main frontman, and won the Golden Boot in his final season in 2011-12.
Manchester United happily met the Gunners’ asking price and suddenly it was revealed that Van Persie had always wanted to play at Old Trafford – much to the discontent of the Arsenal fans.
It didn’t make it any easier for them, either, when he scored 26 goals and led United to their 20th Premier League title in his first season.