Navratilova was a shining example of what could be achieved by defecting from the Soviet-controlled Communism of her native Czechoslovakia to the relative liberty of the United States. Establishing herself as one of the greatest women's tennis players across singles, doubles and mixed doubles helped, but her outspoken personality blossomed in a country with freedom of speech and other basic human rights.
As an 18-year-old, she was stripped of her Czech citizenship in 1975 when she asked the United States for political asylum and was granted temporary residency. She became a US citizen in 1981 but, given the liberalisation of the Czech Republic in recent years, she restored her citizenship in 2008, giving her rights in both countries. Navratilova once said "Whenever people go into politics and try to say Communism was a good thing, I say, 'go ahead and live in a Communist country, if you think it's so great'." She refuses to speak Russian because of the way the Soviets once dominated Eastern Europe.
- Andrew Alderson
4. Sol Campbell
Moving from Tottenham Hotspur to Arsenal is generally not a move good for your health. The two rival North London clubs dislike each other with intensity and, back in 2001 when Campbell defected from Spurs to the Gunners, he was one of Tottenham's leading players and Arsenal were riding the crest of a wave that left Spurs struggling in the backwaters. Centre back Campbell was big, strong and fast and a first-choice England regular but he was also one of the first high-profile Bosman signings in the English Premier League. That ruling meant footballers were free to leave and join another club at their end of their contracted term - which is precisely what Campbell did amid howls of protest from the Spurs faithful. The Bosman ruling also meant that clubs cannot benefit by getting huge transfer fees from such quality players - a double whammy for Spurs. Campbell had to endure many insults and threats and was named No 1 in a list of "football's greatest traitors" by the Daily Mail even in 2009. Still, Campbell had the last laugh - in five years and 195 appearances at Arsenal, he won two Premier League and two FA Cup winners' medals, including the 2001-02 league and FA Cup double, and was in the team known as 'The Invincibles' for their undefeated 2003- 04 league campaign. Campbell was also part of the side that lost 2-1 to Barcelona in the 2006 Champions League final, in which he scored the only goal for Arsenal.
- Paul Lewis
5. Sonny Bill Williams
This wasn't just leaving a club; SBW turned his back on an entire sport when he walked out on the Bulldogs in the dead of night in 2008. Apparently tired of the goldfish bowl life in Sydney, he abandoned it for the quieter rugby climes of Toulon - where, save for an occasional journalist from New Zealand - he was essentially ignored for a couple of years. At the time of his departure, he was just about the biggest name in rugby league - starting to generate headlines off the field as well as on. But it was the manner of his departure that made it the biggest ever defection from league to rugby. Eighteen months into a five-year deal with the Bulldogs, he chose to break the contract. While he found some success in rugby and was part of the All Blacks' victorious World Cup squad, he still appeals as an all-time great in the 13-man code and the Kiwis have been deprived of their No 1 strike weapon since 2008. According to recent unconfirmed reports, SBW is set to jump back into the fish tank next year by rejoining the NRL with the Sydney Roosters, after apparently realising that life in Hamilton with the Chiefs would have a definite 'use by' date.
- Michael Burgess
6. Tonie Carroll
"Faster than Tonie Carroll changes jerseys" became a bit of a catch-cry after Carroll's leap between countries between 2000 and 2004. First, he was an Aussie. Then he was a Kiwi. Then he was an Aussie again. Confused? Born in Christchurch, Carroll played almost all his rugby league in Australia, representing Queensland in State of Origin in 1998 before pledging his allegiance to New Zealand. He played for the Kiwis at the 2000 World Cup but pulled on a Kangaroos jumper in 2004 for the first of his seven tests. In the lead-up to his Kangaroos debut, ironically against the Kiwis, Carroll was asked if he would come in for special attention. "What I cop is what I probably deserve," he said. Amen to that. Carroll, now retired, edges out fellow Aussie Nathan Fien whose "grannygate" scandal in 2006 threatened to derail his defection to New Zealand rugby league. Fien had parentage - his grandmother - giving him the right to play for the Kiwis. Turned out, it was actually his great grandmother and the NZRL had pulled a swifty and then attempted to use legal manoeuvres to prove that grandparents also meant great grandparents. But at least Fien is still playing for the Kiwis...
- Paul Lewis
7. Irene van Dyk
While she has been a godsend for the Silver Ferns, Irene van Dyk's defection was a blow for South African netball. Back in the mid-1990s, van Dyk was raw, never left the circle and didn't "do defence" but she was still an imposing talent. With her in the team, the Proteas beat New Zealand 59-57 in the 1995 world championships, pushing the Ferns into a shock third place. Van Dyk went on to captain her country and played 72 games but swapped nations in 2000, when she and her family decided to emigrate. Back then, netball's eligibility laws meant that the switch was almost instantaneous and she made her Ferns debut a few months later. South Africa hasn't again come close to competing with the major nations, with occasional 50-goal margins, though there were some encouraging signs at the 2011 world championships. Meanwhile, it is estimated van Dyk is responsible for 20 per cent of the goals scored in the entire history of the Silver Ferns. The last time New Zealand won a major international tournament without her was 1987.
- Michael Burgess
8. Shontayne Hape
He was the X factor in the brilliant Kiwis team of 2005; now he is part of the English rugby backline, which features plenty of dancing but no stars. The former Warrior made his name at the Bradford Bulls where he formeda devastating partnership with Lesley Vainikolo, who also enjoyed a successful switch to rugby. The duo scored more than 200 tries between them in five seasons as the Bulls won two grand finals, two world club championships and a Challenge Cup. He won 14 caps for the Kiwis, mostly as centre or wing, though his most memorable match came in the Tri-Nations final of 2005. In a master stroke by coach Brian McClennan, the highly mobile Hape was a last-minute switch to lock forward and played the game of his life in the shock 24-0 win over the Kangaroos. Hape switched to rugby in 2009 and qualified for England on residency grounds. He was an ever-present during the victorious Six Nations campaign last year but never won over fans and critics, who saw his centre partnership with Mike Tindall as overly defensive. Amid the wreckage of England's World Cup campaign, the 30-year-old Hape featured in only one match, scoring two tries against Georgia in pool play. He has already stated that he doesn't expect to be retained by England's new interim coach Stuart Lancaster.
- Michael Burgess
9. Kevin Pietersen
Few players polarise the cricketing public as much as 'KP'. Geoffrey Boycott described him as "cocky and confident" (Boycott should know), whereas Pietersen's former skipper Michael Vaughan told The Guardian, "KP is not a confident person. He obviously has great belief in his ability but that's not quite the same thing . . . I try to text him and talk to him as often as I can because I know he is insecure." Yet England saw Pietersen's talent and got him to see out the four-year stand-down criteria from playing in South Africa. They have been rewarded via his performances which helped England regain the Ashes in 2005. Pietersen, who made his first class debut as a 17-year-old for Natal B in 1997, did not need much convincing to move after having a crack at South Africa's racial quota system for selection. He has not looked back, despite dreadful memories of helping Cannock win the Birmingham and District Premier League in 2000 where, according to The Observer, he despised "those horrible Black Country accents" referring to the dialect of the Midlands, living in a single roomabove a squash court, and working in the club bar. How things have changed these days as one of the highest-paid players in the world.
- Andrew Alderson
10. Michael Owen
There were two clubs and four years in between but Owen's signing with Manchester United in 2009 caused a seismic shock in Lancashire. How could a true Liverpool legend turn out for the Old Trafford club? The rivalry between the Reds and Red Devils remains the biggest and most bitter in English football. No player had transferred directly between the two clubs since Phil Chisnall in 1964. In 2007, Sir Alex Ferguson refused to sell highly rated defender Gabriel Heinze to Liverpool, even though the Argentinian had specifically requested a move to Anfield. Owen scored 118 league goals (216 games) for Liverpool, after first joining as a 14-year-old. Koppites witnessed his development from lightning fast schoolboy to his astonishing displays at the 1998 World Cup and then worldwide acclaim with the Ballon d'Or in 2001. At the time, former Liverpool striker John Aldridge said "signing for [Manchester United] was not something he could do", while fans lauded 'true Scousers' like Steven Gerrard, who famously once showed a film crew his collection of swapped shirts from other clubs,before pointing out that he didn't have a United one and never would. Owen promised he would celebrate if he scored against his former team - but has yet to score against Liverpool.
- Michael Burgess
