Bruno Mars and Mark Ronson have been accused of copying Uptown Funk from a song by 1980s girl group The Sequence.
Kali Bowyer, a representative for the three-piece rap group, claims there are notable similarities between The Sequence's 1979 hit Funk You Up and the 2014 smash hit, which recently won a Grammy Award for Record of the Year. She believes the hooks in both tracks are the same.
They are deliberating over whether to file a lawsuit, according to TMZ.com.
This is not the first time Uptown Funk has been at the centre of plagiarism allegations. Serbian pop star Viktorija - real name Snezana Miskovic - claimed it infringed her 1984 track single Ulice Mracne Nisu Za Devojke, or Dark Streets Are Not For Girls, but never pursued legal action.
At the time, Ronson told Britain's Daily Mirror newspaper: "I don't know what the deal is with that. When you have a hit people always come out of the woodwork to try to claim it. Whatever. I've never had a big hit before so I guess that's what happens."
In 2015, he added five extra songwriting credits onto Uptown Funk to avoid a potential legal case over similarities between the song and The Gap Band's 1979 hit Oops Upside Your Head.
He admits he agreed to do it shortly after Robin Thicke and Pharrell Williams were successfully sued by Marvin Gaye's family for copyright infringement over their song Blurred Lines.
"There's nothing we intentionally or unintentionally took from that song, but that was the settlement we were told to follow... after the Blurred Lines thing, everybody was like, 'You better be careful', and that's kind of all I wanna say about it," Ronson previously told Britain's Daily Telegraph newspaper.