An Australian expert has told a race-fixing trial that jockey Kieren Fallon's ride during a race in question was "quite extraordinary".
Ray Murrihy spoke after the Old Bailey jury watched footage of Fallon's mount, Ballinger Ridge, losing a race in the final strides after being eased down.
The defence has already admitted Mr Fallon made a "howler" on the horse.
Six defendants deny conspiracy to defraud customers of the internet betting exchange Betfair.
Ballinger Ridge is one of 27 horses Mr Fallon and fellow jockeys Fergal Lynch and Darren Williams are alleged to have conspired to lose on.
The prosecution claim the conspiracy was led by South Yorkshire businessman Miles Rodgers, who laid bets - or bet to lose - on the internet exchange Betfair.
The jury watched as Mr Fallon - a former champion jockey - built up a lead of eight lengths in a race at Lingfield Park in March 2004 only to be caught on the line by a horse called Rye.
Mr Murrihy said: "That is a quite extraordinary ride.
"I don't think I have ever in my experience seen a horse eased down in that part of the race and it undoubtedly cost him the win."
Earlier Mr Murrihy, a key prosecution witness, outlined his credentials. He said he had worked in racing since 1970 and had been the top professional steward in New South Wales since 1995.
He said: "I've never tried to tally up how many races I've watched but it does encompass those 37 years."
'Difficult to spot'
Mr Murrihy, who stressed that he saw himself as an independent witness with no connections to the British racing industry, said it was "typically quite difficult" to spot a jockey deliberately stopping a horse.
Asked by Jonathan Caplan QC how a jockey might stop a horse, he said there were many ways and he said it was unlikely they would do anything as blatant as physically restrain a horse.
He said among the tactics they could adopt to damage a horse's chances of winning were tracking too wide, letting a horse run too freely at the start of the race or holding up a horse which was naturally a front runner.
The court was shown footage of a number of the 27 races in the indictment.
Mr Murrihy said he would have ordered stewards' inquiries in 13 of the 27 races, including the Ballinger Ridge race.
Earlier in the trial Mr Fallon's counsel, John Kelsey-Fry QC, conceded that his client had been "vilified" in the racing press for his ride on Ballinger Ridge.
He said: "He got off and was very apologetic and said I have screwed up."
But Mr Kelsey-Fry said his client denied losing deliberately or any of the other races in question.
Mr Fallon, Mr Rodgers and Mr Lynch, as well as Mr Lynch's brother Shaun Lynch, 37, of Londonderry, Northern Ireland, Darren Williams, 29, of Leyburn, North Yorkshire and Philip Sherkle, 42, of Tamworth, Staffordshire, have all pleaded not guilty to being involved in the conspiracy.