James Arthur has been accused of copying his X Factor performance of Sexy And I Know it from YouTube star Noah.
James wowed the judges on Saturday night with his take on the LMFAO or, as Louis put it, LMFO, track for club classics week.
Gary Barlow said: "You turned that song on it’s head. It’s a silly dance song but you gave those lyrics meaning tonight."
And he gushed: "This wasn’t the performance of the night, it was the performance of the series so far."
Louis Walsh added: "James Arthur, what a brilliant interpretation. You are a real professional, you had a tough week but when you get on that stage you own it."
But some viewers recognised the cover from YouTube singer Noah, who uploaded a very similar version back in May, and has gone on to achieve over 13 million views of the performance.
One angry fan wrote: "All work is done by Noah and James gets the fame! This makes me feel sick in my stomach!"
Interestingly, it's not the first time that an X Factor act has been accused of copying the song.
It was claimed earlier this year that X Factor USA star Cece pinched her judges' houses performance from Noah too.
The youngster was singing the LMFAO song for Demi Lavato on the US show earlier this month.
Listen to Noah and James' performances below and tell us what you think, who do you prefer?
The X Factor 2012 continues this Saturday night with a spooky Halloween themed episode as the remaining ten contestants perform live once again.
The latest results show follows on Sunday when one more act will be given the boot.