London - Premier League champions Leicester's shambolic defence of their title leaves them in real danger of relegation - they would not be the first to have seen a fairytale sporting success quickly decline into a nightmare.
Here are five other examples:
Boxing - Buster Douglas
James 'Buster' Douglas tamed the fearsome 'Iron' Mike Tyson in Tokyo in 1990, the 42/1 outsider inflicting his first defeat and becoming undisputed heavyweight world champion. Douglas, whose preparation had been upset by the loss of his mother, was unable to summon up that same intensity nearly a year later as his first defence ended in defeat to Evander Holyfield, who knocked him out in the third round. The only intensity he came up with was to balloon in size till he came close to dying. That sparked him out of his lassitude but despite winning several bouts on returning to the ring there was never a likelihood he would regain the golden touch that for just one memorable night in Japan had earned him his place in the history books.
Cricket - England team
In a bizarre piece of scheduling there were two Ashes series set for 2013. England generally outplayed Australia in the series they hosted winning 3-0 and came close to a first ever 4-0 success. That Aussie side were labelled the worst to have toured England. Months later England were to return shell-shocked as the revitalised Aussies, not far removed from the same group of players humiliated in England, had turned things round in remarkable fashion and whitewashed them 5-0 Down Under in a series that stretched into 2014. Until the recent 4-0 series loss to India it was probably the lowest point of England's fortunes under skipper Alastair Cook.
Golf - Ian Baker-Finch
Debonair Australian golfer looked to be on the trajectory to greater things when he captured the 1991 British Open aged 31. However, it was to prove to be the peak as very rapidly he descended into the equivalent of Dantes Inferno in terms of his game and form. He won a couple of times on the less competitive Australia tour but in the cauldron of the PGA Tour and the Majors he played without any confidence at all. He reached his nadir in the 1997 British Open shooting an opening 92 and in despair in the locker room he cried and then announced tournament golf was over for him. "I felt like I was walking naked, like the grass was taller than me," Baker-Finch told golftoday.uk. "I tried to walk with my head high. It was really hard."
Racing - Norton's Coin
Fairy-tale win in the 1990 Cheltenham Gold Cup the 'blue riband' of steeple-chasing for the unglamorous 100/1 shot, trained by Welsh dairy farmer Sirrell Griffiths, whose stable ran to just two horses and which clearly impressed avid racing fan the Queen Mother, who presented the trophy. "She said to me 'I think it's marvellous to think that you've only got two horses and you can win a race like this," recalled Griffiths in 2015. Norton's Coin won just once in 18 more starts, not even riding legend Lester Piggott could conjure some magic out of him when he ran over the flat at Royal Ascot.
Football - Nuremberg
Nuremberg made sporting headlines in 1968 when they captured the Bundesliga title under coach Max Merkel. However, Merkel unlike Claudio Ranieri with his Leicester squad didn't retain faith in them and sold many of the title winners, including leading scorer Franz Brungs, whilst bringing in 11 fresh faces. However, it rebounded on him catastrophically as they struggled from the start and whilst they were far from certainties to go down he was sent packing with several games remaining, internal unrest was suspected to be the final straw. His departure did not stop the trot and they were relegated at the end of the season.