Adam Scott was backed at a low of 1.02 in-running on Betfair before being pipped to the Open Championship by Ernie Els.
Scott held a four-shot lead with four holes to play in the final round but bogeyed 15, 16, 17 and 18 to leave Els the winning by one stroke at Royal Lytham.
More than £25,000 was matched at 1.02, with a further £424,000 traded at 1.03.
Els, who started the day seven shots off Scott's lead, birdied his final hole to turn the heat up on the Australian and it worked.
He was matched at a high of 470 on the exchange before lifting the Claret Jug for the second time - the first coming back in 2002 at Muirfield, a course which will stage the event again next year.
BetVictor were one of the firms who quickly priced up the 2013 championship, making Els 33/1 to defend his title.
Tiger Woods, who finished in a tie for third at Lytham, is their 9/1 favourite.
