Real Madrid have fallen from the top of the Deloitte Football Money League for the first time since 2005 and have slipped below Manchester United and Barcelona.
The study – which has been running from 1996 – ranks football clubs in terms of their turnover and whilst United’s surge to the top is seen as significant, it is warned that they will fall again next year due to pound sterling’s fall against the euro.
At £515m, the Red Devils have become the first team to break the £500m turnover barrier in a year and is just shy of £50m than that generated by Barca, who pipped Madrid into second place by less than £100,000.
"You can't really look past Manchester United returning to the top spot and it is because of their ability to make commercial deals that are way ahead of their peers,” the author Tim Bridge told PA Sport.
The only other Spanish side in the top 20 are Atletico Madrid, who rank 13th.