51Âþ»­

winning the Premier League is one of the biggest achievements against the odds in the history of sport, says a 51Âþ»­ Leicester (51Âþ»­) expert.

says shocks such as Buster Douglas beating an 'undefeatable' Mike Tyson in boxing in 1990 or Chelsea losing 4-2 to Bradford in last year's FA Cup are liable to happen because they are one-offs.

Bradford City's Mark Yeates celebrates with teammates: John Walton/PA Wire

However, Leicester's success is a different type of sporting upset and a much more sustained achievement because of the nature of the Premier League, involving 38 fixtures played over 10 months.

Neil, senior research fellow at the , said: "A shock in the FA Cup is just one game whereas Leicester is playing over a whole season. It's a much greater achievement against the odds.

"Because of the sporting integrity of the Premier League, where every team plays each other home and away over 38 games, the impact of luck and chance is reduced."

There are only a select few similar-sized clubs who have won their respective football leagues in recent times:

• Hellas Verona, who won the Serie A Championship, the Italian league, in 1985, despite opposition from the usually dominant AC Milan, Juventus and Inter Milan
• Unfashionable Deportivo de La Coruña, who in 2000 topped La Liga, the Spanish league that was usually led by Barcelona and Real Madrid
• Boavista, who snatched the top spot in the Portuguese Primeira Liga in 2001 from 'the big three' - SL Benfica, FC Porto and Sporting Lisbon
• FC Twente, managed by Steve McClaren, who beat usual favourites AFC Ajax, PSV Eindhoven and Feyenoord to triumph in the Eredivisie, the Dutch league, in 2010

Deportivo players and fans celebrate winning the Spanish league

Reassuringly for Foxes fans, their successes didn't just come and go - FC Twente were runners-up the following year while Deportivo were in the top three for the next four years.

Like Leicester, 5,000-1 outsiders at the start of the season, no one would have put money on these teams seeing it through to the end.

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Neil, author of The Football Manager: A History (Routledge, 2006) and Editor-in-Chief of the journal,  Sport in History, said: "Bookmakers don't usually get it wrong!

"A combination of factors, including the team coming together, playing above themselves and the opposition underperforming, led to these unexpected sporting triumphs."

Neil says another comparable 'shock' in footballing achievements is Nottingham Forest winning two European Cups in 1979 and 1980.

"To do this twice is an achievement. Other big European teams at the time didn't win twice in a row.

"That is on a par with what Leicester achieved, in an age when teams do spend a lot of money on players and the best playing talent is concentrated in fewer and fewer clubs."

Here are some of the widely-considered greatest upsets in sporting history:

• Football’s first big shock, Walsall beating Arsenal in the FA Cup in 1933
• North Korea beating Italy 1-0 in the 1966 World Cup
• Leigh winning the 1971 Rugby League Challenge Cup after a 24-7 victory over Leeds, who had 14 internationals in their squad
• Miracle on Ice, when the USA defeated the Soviet Union 4-3 in the 1980 Winter Olympics men’s ice hockey with a team made up of college students
• Keith Deller hitting the doubles to beat favourite Eric Bristow in the 1983 World Professional Darts Championship, the first qualifier and youngest player to win the title
• The America’s Cup, so-named because it had never been won by anyone other America, until 1983, when Australia sailed off with the title
• The 1983 Prudential World Cup cricket final, which saw India beat the West Indies, the most dominant team in the world

• Dennis Taylor staging a comeback from 8-0 down to pot the last black of the 35^th frame in the early hours to beat World No. 1 and three-time winner Steve Davis in the 1985 Snooker World Championship
• American Rulon Gardner beating Russian Aleksandr Karelin, undefeated for 13 years, in Greco-Roman wrestling at the Sydney Olympics in 2000
• Celtic losing 3-1 to Caledonian Thistle in 2000 – prompting the famous newspaper headline Super Caley Go Ballistic Celtic Are Atrocious
• Japan, who were trailing 32-29 with just minutes remaining, and went on to beat two-time champions South Africa in last year’s Rugby Union World Cup