Manchester United had topped the chart since its creation nine years ago but latest figures, relating to the 2004-2005 season, put Real Madrid, which is now worth 拢186.2m, top and the English club, now worth 拢166.4m, second.
Dan Jones, a partner in Deloitte's sports business group, said Beckham's switch to Real Madrid from Man United in 2003 has been a key factor, as well as a concerted effort by the Spanish club to boost its commercial revenues.
The England captain's arrival at the Spanish club boosted its merchandising power and the world standing of its brand.
Jones said: "It's startling how successful Madrid has been in growing revenue and, over the last two years, it has been about commercial growth and merchandising.
"Beckham has been a major factor in that. You can't put a figure on his impact, he's the most famous player in the world."
The Deloitte league measures revenues, including gate receipts and broadcasting rights, rather than profits or spending power.
Deloitte suggests though that Real will be under pressure to retain its top spot. Despite suffering an early exit from the lucrative Champions League this year, Man United is set to significantly boost revenue with an extension to its Old Trafford stadium, which will take its capacity above the 70,000 mark.
It is also speculated that German clubs are also set to benefit in coming years, with significant investment in stadia already taking place for this year's World Cup.
Other English clubs in this latest money league include Chelsea, which is worth 拢149.1m and dropped a place to fifth, Liverpool in eighth with 拢122.4m and Arsenal taking 10th place with 拢115.7m.
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