Jockey Neil Callan held his hands up to an "embarrassing" blunder after he rode a finish a circuit too soon.
The sportsman misjudged the distance of an all-weather race at Kempton teaming up with outsider Ballet Blanc.
Callan took the lead on the 50-1 shot after just three furlongs of the two-mile contest on Wednesday evening. From the widest stall in ten, Callan brought his mount around rivals and went for the drive position at the two furlong pole.
He pushed the Amanda Perrett-owned and trained filly clear of fellow outsider Tribal Commander as the winning post loomed.
"Ballet Blanc is clear by about five lengths but they still have got a circuit to go!" said commentator Mark Johnson.
Callan then eased his horse down, believing he had won comfortably on the longshot. Moments later, he realised his mistake when he looked around and saw his nine weighing room colleagues taking their horses out for another lap of the Surrey track.
Using a facepalm emoji, Callan tweeted in response to footage of the replay: "Yep that was embarrassing!!"
The stewards handed him a lengthy suspension for the blip in the race won by the 9-4 favourite Blazeon Five.
Callan had earlier enjoyed two winners, Tenjin for Marco Botti and Lelabad from William Knight's stable.
Their report read: "Neil Callan, the rider of Ballet Blanc, unplaced, had appeared to ride a finish a circuit too soon. After being interviewed and shown recordings of the incident, the rider was suspended for 12 days."
In five runs, Ballet Blanc has placed once and was set to race over the longest trip of her career on the night.
She eventually completed and was tailed off, 86 lengths behind the ninth-placed horse.
Dozens of punters shared the footage and reacted to the events that unfolded at the end of the eight-race card.
One wrote: "Neil Callan suspended for 12 days for thinking the race was 5f not 2 miles..."
Another pointed out the bemused nature of Johnson's reaction to the error.
With several laugher emojis, they wrote: "commentary makes this I must say haha."
And a third person added: "Callan has had a shocker here."
Callan returned to ride in the UK in 2021 after spending 11 years in Hong Kong, where he rode 282 winners. He earned more than £30million in prize money and the nickname 'Iron Man' from fans of the sport.
Prior to the successful venture abroad, he spent more than two decades competing in Britain and his Group 1 winners included Borderlescott in the 2009 Nunthorpe Stakes.
