England's Paul Casey has apologised for saying he "hated" Americans after receiving a flood of "nasty" e-mails which prevented him from sleeping.
"I'd like to apologise and do everything I could to take it back," said Casey, who lives in the USA and has an American coach and girlfriend.
"It's made people angry, which I fully understand, and it's made me angry and upset. I've had nasty stuff on e-mail.
"The word 'hate' was my error. I shouldn't have used it."
Casey, who played college golf at Arizona State and lives in Scottsdale, admitted the past two days had been "a horrible experience".
"I've had lots of comments," he said. "Most of them I won't repeat, but
99.9% of them have made me regret what I said.
"The story's run though, and there's nothing I can do to correct it. If I could I would.
"I have nothing against the United States whatsoever and I wish I could take
it back. I struggled to get to sleep and it weighed on my mind this morning."
Casey told a Sunday newspaper he "hated Americans" but on Wedneday claimed it was a tongue-in-cheek reference to Europe's Ryder Cup motivation methods.
"They do have a tendency to wind people up," he said.
"When they are chanting 'USA' and there's lots of them it just makes you want to beat them even more.
"That's the point I was trying to get across. They probably failed to realise it really sort of riles us and the rest of the world."
The fall-out from Casey's comments did not prevent him and partner Luke Donald scoring an 11-under-par 61 in the opening fourballs of the World Cup in Spain, to trail Ireland and Austria by only one.
Donald, who also enjoyed a successful US collegiate golf career and lives in Chicago with an American girlfriend, sympathised with Casey.
"I think people who are not Americans can get upset with Americans quite easily," he said.
"They do seem to be very insular and make rash comments that are really quite upsetting sometimes."
Donald used as an example comments made by American Tour player Ryan Palmer, who said shortly after the Ryder Cup that the Nationwide Tour - the second division in America -
was the second strongest tour in the world.
"Those kind of comments force people like Paul to say what he says, I would
have thought," said Donald.
"I guess it's a reaction to the American way of thinking that they have the best country in the world and don't really need to leave their country. They have everything.
"I think a lot of Americans could gain a lot by exploring the world a little bit more."
Casey's Ryder Cup team-mate Paul McGinley of Ireland was less sympathetic, however.
"Hate is a bad word to use - a terrible thing in sport," he said. "I don't want to stir up any animosity."
US player Scott Verplank insisted Casey's remarks could land him in hot water on the US Tour.
"If he's really that uncomfortable or that annoyed, I don't think anybody would miss him if he went back to England," said Verplank.
"I wouldn't think this is the smartest thing to do if you're going to stay over in the United States.
"How can you say derogatory things towards a group of people and not expect some guys to take it personally?"