The strength of the euro against the pound has helped Real Madrid maintain their position at the top, despite a 21% increase in revenue for United, according to the Deloitte Football Money League.
United are due to announce their figures shortly, but Deloitte are predicting the club will reveal revenue of £257million in 2007/08 compared to £210million in the previous 12 months.
Dan Jones, partner in the Sports Business Group at Deloitte, said: "Real Madrid's 4% revenue growth is more modest than recent years, but the club have doubled their revenues since 2002 and have a lead of £32.5m over Manchester United.
"Real have announced they are budgeting for revenues of 400m euro (£360m) in 2008/09, so it will be difficult for rivals to replace them at the top of the Money League next year.
"Manchester United's success in winning the Premier League and Champions League has contributed to significantly-increased revenue in 2007/08, but the depreciation of the pound against the euro means they remain in second position."
All the English clubs suffered from the currency issue - Barcelona's revenue increased by only 6%, while Chelsea and Arsenal enjoyed rises of 11.5% and 18% respectively yet both Premier Leagues sides saw themselves fall a place. Liverpool, however, have gone up a place to seventh with a 25% rise in turnover.
Jones added: "If the value of the pound had not depreciated, there would have been nine, rather than seven English clubs in the top 20 - and Manchester United would have topped the Money League ahead of Real Madrid."
Deloitte Football Money League (2007/08 revenue)
1 (last year - 1) Real Madrid £289.6m
2 (2) Manchester United £257.1m
3 (3) FC Barcelona £244.4m
4 (7) Bayern Munich £233.8m
5 (4) Chelsea £212.9m
6 (5) Arsenal £209.3m
7 (8) Liverpool £167.0m
8 (6) AC Milan £165.8m
9 (11) AS Roma £138.9m
10 (9) Internazionale £136.9m
11 (12) Juventus £132.6m
12 (13) Lyon £123.3m
13 (16) Schalke 04 £117.5m
14 (10) Tottenham £114.8m
15 (15) Hamburg £101.3m
16 (19) Marseille £100.4m
17 (14) Newcastle £99.4m
18 (-) Stuttgart £88.3m
19 (-) Fenerbahce £88.1m
20 (-) Manchester City £82.3m