Mark Roe and Jesper Parnevik have been disqualified from the Open at Sandwich after a mix-up with their scorecards.
The two players failed to exchange scorecards before the first hole of their third round at Royal St George's and therefore signed for incorrect scores at the end of their rounds.
Roe hit a 67, equalling Nick Faldo's best round of the championship so far, to
finish just one over par.
At the time when his mistake was discovered, the English golfer was lying just three shots off the lead.
If the error had been spotted before the players had signed for their cards and left the scorers' hut, then they would not have been disqualified.
Parnevik criticised rule 6D, which brought about the players' disqualification and said that Royal & Ancient officials (who oversee the implementation of golf's rules at the Open) should have spotted the mistake before the players left the hut.
"It think it's really, really dumb," the Swede told the BBC. "I feel so bad for Mark Roe."
"They are so thorough here. We got the all-clear to leave the hut. Of course it's our fault but I can't believe the R&A didn't catch it."
Despite his obvious disappointment, Roe was more philosophical about the incident.
"What can you do? I've just played one of the greatest rounds of my life and
I can't play tomorrow," said the 40-year-old.
"I am usually very diligent. It's a freak - I've never done it before in my
life. But that's life. I'll go home now and see my wife and kids.
"The tournament goes
on and life goes on. I guess I feel a bit numb. Rules are rules and they are there to protect the
game. I'm not bigger than the game," he added.
R&A secretary Peter Dawson said he sympathised with the players and accepted some of the blame for the mix-up.
"It's one of the great tragedies of championship golf. Our checking procedures have clearly failed and we take some blame, but not responsibility," he said.
"We feel very bad about this. We like to think we have procedures in place -
we have stopped a number of players being disqualified already this week - and
we will be looking at them very hard."
Both world number one Tiger Woods and Sergio Garcia offered their sympathies to the disqualified players and suggested that the European Tour change their regulations to prevent any further mishaps.
"They have given us our own cards every day," said Woods, "and we're not used to that, we're usually given someone else's."
Garcia added: "If they give us the cards the opposite way round it would make it a little bit easier."
The last time a scorecard error cost somebody the chance of a big win was
Padraig Harrington at the 2000 Benson & Hedges International Open.
Harrington led by five with a round to play but it was discovered by chance that he
had not signed his first round scorecard.
Ian Woosnam was docked two shots for having an extra club in his bag at the Open two years ago but went on to finish joint third.
At the 1968 Masters Roberto de Vicenzo should have tied with Bob Goalby and
gone into a play-off when it was discovered he had signed for a wrong score at
one hole - but he was allowed to keep second place.