James Arthur wowed the judges and the crowd with his rendition of LMFAO's dance hit, Sexy And I Know It.
The judges were full of praise as Gary Barlow said, "You turned that song on it's head. It's a silly dance song but you gave those lyrics meaning tonight."
He added, "This wasn't the performance of the night, it was the performance of the series so far."
Louis Walsh said, "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 a few fans noticed that his version was very similar to something that they had heard before.
YouTube sensation only1noah did a cover of the track on 9 May 2012 which has racked up over 13 million hits.
Fans have commented their anger about James being given credit for the cover with one fan saying, "complete joke that he sung it TWICE, once at the judges houses and now on the live shows, with no mention of it being a cover of Noah's.
"Also Noah commented on the judges houses video of james :'Great job on your cover of my cover. :)', the comment was removed within 24 hours. What a disgrace.
"On the xfactor videos they also say that you can downlooad jame's version off itunes, not to mention the phone calls voting for him. They're making money off Noah's genius. Lost so much respect for James."
While James never claimed that the version was his own, the judges praised him for his interpretation and slightly allowed the viewers to believe that it was James' re-visioning of the song.
Plus the fact James' performance can be downloaded on iTunes might be a issue for Noah...
Listen to both version below and let us know what you think!
JAMES ARTHUR ADMITS USING YOUTUBE STARS COVER
MK1 KICKED OFF THE X FACTOR
NICOLE SCHERZINGER DOES ALEXANDER MCQUEEN