Real remain at the top of the league for the third successive year on the latest figures available, from the 2006-07 season, which showed their revenue increased by 20 per cent to £236million.
However, United enjoyed an even bigger percentage increase to come in second at £212million, two places up on the previous season and ahead of Barcelona, Chelsea and Arsenal in third, fourth and fifth respectively.
The Old Trafford club had dominated the money league since its inception in 1996-97 before Real took over, and Paul Rawnsley, director of Deloitte's sports business group, believes it is only a matter of time before they resume their position at the top with the impact of the new television deal due to be felt during the current campaign.
He said: "Real Madrid are still at the top after an impressive 20 per cent growth in revenue, but Manchester United closed the gap and have the potential to catch Real up and take that top spot possibly next season or the season thereafter.
"To some extent, that will depend on how they perform relative to Real Madrid in the Champions League."
With the new television money to be factored in, Rawnsley said: "We would expect to see as many as 10 of the top 20 being made up by English Premier League clubs in next year's table.
"There are different ways of measuring the health and quality of the league, but there has been period of strong financial growth in terms of broadcasting rights and matchday and commercial revenues.
"Yes, the clubs spend a lot of money on wages, but overall, the Premier League clubs are profitable.
"It is a different story lower down the leagues, but the Premier League is the highest revenue-generating league in the world."
Premier League chiefs admitted last week that they are examining the possibility of playing a 39th round of matches outside England as they look to new revenue sources.
Rawnsley admitted that as long as the brands of both the league itself and individual clubs remain attractive, English clubs can continue to dominate.
He said: "In terms of the quality of the football and the quality of the competition, that is sustainable.
"It continues to have strength here in England and continues to grow in strength in terms of people wanting to watch matches and wanting to be associated with the English Premier League clubs and English football around the world.
"That could be fans overseas watching it on television and driving up the television rights, it could be sponsors from the USA or Asia or wherever else in the world who want to be associated with the game.
"But there is a balance to be struck. Fans want to see their club winning football matches and winning trophies because that is what football is all about.
"But on the business side of the game, clubs are competing against each other for players, and to able to get better players, they need and want to have more revenue.
"Exploiting their brand value, not just here but around the world, can generate that revenue.
"The football side and the business side are very much inter-related, but there is a balance that does need to be achieved."
1 Real Madrid £236.2m
2 Man Utd £212.1m
3 Barcelona £195.3m
4 Chelsea £190.5m
5 Arsenal £177.6m
6 AC Milan £153m
7 Bayern Munich £150.3m
8 Liverpool £133.9m
9 Internazionale £131.3m
10 AS Roma £106.1m
11 Tottenham £103.1m
12 Juventus £97.7m
13 Lyons £94.6m
14 Newcastle £87.1m
15 Hamburg SV £81.0m
16 Schalke 04 £76.9m
17 Celtic £75.2m
18 Valencia £72.4m
19 Marseille £66.6m
20 Werder Bremen £65.5m