The lawyer for jockey Kieren Fallon has told a court the race-fixing case against his client was "absurd".
Mr Fallon, who won France's biggest race at the weekend, denies the allegations
The prosecution claims Mr Fallon and two jockeys conspired to lose 27 races between December 2002 and August 2004.
But John Kelsey-Fry QC told the Old Bailey Mr Fallon's winning rate in those races was much higher than in others he entered.
Six defendants, including Mr Fallon, deny conspiracy to defraud customers of internet betting exchange Betfair.
Mr Kelsey-Fry said police had misinterpreted snippets of conversation and spun them into a conspiracy.
'Driven by desire to win'
He said his client had been a champion jockey six times and added "he is a man driven by a desire to win".
He pointed out Mr Fallon's average strike rate on horses between 2002 and 2004 was 19%.
But it rose to 29.4% in the races which are included in the indictment.
He said: "That means that if the Crown's allegation is right, that Fallon's win rate was 150% higher when he was trying to lose than when he was trying to win."
Mr Kelsey-Fry said the allegation was "simply ridiculous" and he pointed out that trainer Sir Michael Stoute had praised Mr Fallon's "tremendous ride" on Russian Rhythm, which won a race Mr Fallon is said to have conspired to lose.
He said horse racing is a sport based on opinions and pointed out that on 7 October, Mr Fallon had expressed his own opinion to the BBC's Clare Balding just before riding Dylan Thomas in the Prix de l'Arc de Triomphe at Longchamp.
Mr Fallon, 42, of Tipperary, Republic of Ireland, had told Ms Balding the ground was too soft for his mount and he would have rather been aboard his horse's stablemate Soldier of Fortune.
Mr Kelsey-Fry said Mr Fallon had sounded "positively depressed" and added "anyone watching that would have thought Kieran Fallon was going to lose.
All six defendants deny there was any conspiracy
"If [co-defendant Miles Rodgers] had been watching, he would have probably have rushed off to lay the horse.
"Half an hour later, Mr Fallon won on Dylan Thomas."
Laying the horse is a racing term which means backing a horse to lose.
Mr Kelsey-Fry had admitted his client had discussed various horses with co-defendants Fergal Lynch, Darren Williams and Philip Sherkle.
"He was willing to share opinions with Mr Sherkle - who was a friend - about who he fancied and who he didn't fancy.
"It was not a corrupt relationship. There was nothing wrong with it. The whole world wants to know his opinion on horses."
Mr Kelsey-Fry referred in court to a race in Newmarket in July 2004, which Mr Fallon rode a horse called Daring Aim - owned by the Queen.
He said: "If ever there was a horse which Kieren Fallon could have chosen to lose on, it was Daring Aim.
"And if ever there was a race which showed why he was a champion jockey, it was this one.
"Daring Aim was a cussed, difficult, reluctant filly up against a heavily backed favourite."
He then went on to quote the race report from the following day's Racing Post, which described the horse as being "kept about her business" by Mr Fallon, who was "not about to admit defeat".
He said the Daring Aim race had been a gilt-edged opportunity to lose without attracting any criticism, but Mr Fallon showed all his skills to win the race.
Mr Kelsey-Fry also pointed out there had been no stewards' inquiries into any of the 17 races involving Mr Fallon.
Mr Fallon, Miles Rodgers, 38, from Silkstone, South Yorkshire, and Fergal Lynch, 29, from Boroughbridge, North Yorkshire, Mr Lynch's brother Shaun Lynch, 37, of Londonderry, Northern Ireland, Mr Sherkle, 42, of Tamworth, Staffordshire and Mr Williams, 29, of Leyburn, North Yorkshire, have all pleaded not guilty to being involved in the alleged race-fixing scam.
Mr Rodgers also denies concealing the proceeds of crime.
The trial continues.