David Cameron has apologised for experiencing "brain fade" after he forgot which football team he supports.
Mr Cameron said he supported West Ham during a speech in south London - despite previously claiming he is a fan of Aston Villa.
Giving a speech on ethnic minorities, the Prime Minister said: "You can support Man Utd, the West Indies and Team GB all at the same time - of course I'd rather you supported West Ham."
The only similarity between the two Premier League sides is that they both play in claret and blue.
Asked to clarify to his football allegiances, Mr Cameron said he had experienced "brain fade".
The Conservative Party confirmed the football reference was not included in the Prime Minister's prepared speech but was an off the cuff remark.
"I had what Natalie Bennett described as a brain fade," Mr Cameron said.
"I'm a Villa fan ... I must have been overcome by something ... this morning. But there we are, these things sometimes happen when you are on the stump."
The gaffe soon began trending as #villagate on Twitter with Mr Cameron's critics, including shadow chancellor Ed Balls and Alastair Campbell, seizing on the error.
Ukip leader Nigel Farage, who is a Crystal Palace fan, poked fun at Mr Cameron as he arrived at an event in London, ITV News' Rohit Kachroo reported.
Mr Cameron later insisted that he had been a Villa fan "all my life" and did not know why he mistakenly pledged his support for West Ham.
"I've been an Aston Villa fan all my life, I literally opened my mouth and I was going off-piste about the fact that in Britain you can be a supporter of the West Indies, a supporter of Manchester United, and a supporter of Team GB," he told Sky News.
"I was then busking about other things you can support and was ... I don't know what happened to me, it was just one of those things."