As Manchester United and Real Madrid do battle in the Champions League, the International Federation of Football History and Statistics (IFFHS) have released their official club world and the shocking results can be seen by clicking the arrow above.
The IFFHS - which chronicles the history and statistics around the world and has its work recognised by FIFA - ranks the world's top-flight clubs by considering their results over a 12-month period, looking at continental, intercontinental and domestic league matches, as well as those in each club's most important domestic cup competition.
Each country is categorised into one of four levels based on national league performance, with clubs in the highest ranked league receiving four points for a win, two for a draw and zero for a defeat.
Continental competitions are ranked in a similar fashion, with the highest level competitions (Champions League and Copa Libertadores) yielding 14 points for a win and seven for a draw for all teams competing, regardless of the weighting of their domestic leagues. The second tier of continental football (Europa League and Copa Sudamericana) awards 12 points for a win and six for a draw.
The most points a club side can gain from a fixture is the Club World Cup Final, last year contested between Chelsea and Corinthians, which results in 21 points for the victor.
The result is a system for ranking club sides (to read more on how the calculations are made, click here). To find out who is the world's number one side, click the arrow above.
Do you agree with the ranking system? Who do you think is the world's number one side at the moment? Let us know by commenting below.