The London International Horse Show ended in controversial fashion after Irish sensation Bertram Allen was disqualified from the Olympia Grand Prix.
Allen, 20, had posted a stunning jump-off time of 30.45 seconds on Quiet Easy to destroy a world-class field.
But drama then reigned behind the scenes amid reports that Allen had been disqualified after blood had apparently been spotted on one of the horse's flanks, raising a horse welfare issue.
Under international rules, a rider is automatically disqualified if blood is found.
The prize presentation ceremony did not take place until 30 minutes after the class ended, with a capacity 9,000 crowd remaining in their seats, awaiting developments.
Heated discussion raged around the collecting ring, but Britain's Michael Whitaker, riding Viking, was promoted from second place to take the £18,300 top prize, with Germans Ludger Beerbaum and Marcus Ehning second and third, respectively.
Olympia officials were believed to be drafting a statement explaining the sequence of events as Allen, who is one of showjumping's hottest young properties, began reflecting on matters.
All horses are checked by the steward after they have jumped, and any issues are then reported to the ground jury, who would make a final decision.
Allen, though, was left stunned, as were connections of the horse, an 11-year-old chestnut gelding.
"I am utterly devastated, just speechless," Allen told www.horseandhound.co.uk.
"I have a fantastic relationship with all of my horses, and their welfare is paramount.
"My foot must have slipped against Quiet Easy's side as I was riding against the clock. He's a sensitive horse and it was just a tiny nick."
Whitaker, meanwhile, gave Allen his winner's rosette, and said: "Bertram was probably very hard done-by.
"I would have preferred to have won it in the ring, but I suppose rules are rules and everyone has got to abide by them, but I couldn't see much wrong."
There was a disqualification earlier on Monday in the International Six Bar competition, meanwhile, affecting Norway's Victoria Gulliksen, who had tied for victory with Spain's Eduardo Alvarez Aznar.
Organisers said 23-year-old Gulliksen had entered the competition when the rules had specifically stated that she could not do so. Gulliksen was only invited to take part in Olympia's Alltech Puissance event last Thursday.
Gulliksen said: "Sadly, there was a mistake, on my part, as I genuinely thought my National Federation had received permission for me to enter the Six Bar."
The event's ground jury spotted the error, but it was too late to take action. Gulliksen was subsequently disqualified under the competition rules.
Ground jury president Jon Doney added: "Unfortunately, under the rules, there is no question that Victoria Gulliksen has had to be disqualified from the Six Bar competition today.
"We are obviously very disappointed for Victoria and the genuine mistake which led to the disqualification, and look forward to her returning another year."
Ten combinations took on the challenge, which involves jumping a line of fences, with the final obstacle steadily raised and a maximum of four jump-off rounds being allowed, with Alvarez Aznar on Chatman and Gulliksen, riding Grand Balou, both jumping a final fence of 6ft 5in high.
Switzerland's former world number one Pius Schwizer had made a flying start to the show's final at Olympia by winning a thrilling Holly Speed Stakes.
Just 60 hundredths of a second separated the top four finishers in the one round speed class. and it was Schwizer who came up trumps, clocking a time of 52.34 seconds on Leonard de la Ferme to edge out Irish 2012 Olympic bronze medallist Cian O'Connor, riding Coco II.
Allen's fellow Irish star Cian O'Connor, who also rode in the grand prix, criticised the decision to disqualify Allen.
Writing on his Facebook page, London 2012 individual bronze medallist O'Connor said: "I feel for my team-mate Bertram tonight, who annihilated the opposition to win the grand prix.
"A general consensus among the top riders here is that the FEI (Federation Equestre Internationale) rule needs to be reviewed regarding mandatory disqualification, and in my view, over-zealous stewarding by one particular steward, compounded by the apathetic actions of the foreign judge and president of the ground jury, led to bringing the sport and this great show into the spotlight for the wrong reasons."