David Gill claims Manchester City will never be as big as United in Asia and other markets across the globe.
The former Manchester United chief executive questioned the pulling power of City in the Far East as he spoke at an event to celebrate 500 years of Manchester Grammar School.
Gill, quoted by the Manchester Evening News, said: "I'm not being arrogant here but (Manchester City) will never be as big as Manchester United in Asia and certain markets.
"Look at Liverpool, the club haven't won the league for so many years, but they are very popular in Asia.
"The big teams with history and heritage, Barcelona, Bayern Munich, Juventus and Real Madrid, have that."
Gill, who stood down as United chief executive in 2013, added: " If Sheikh Mansour decided he wanted to sell the club tomorrow, what he's left there, in terms of the development of that whole area, is unbelievable and is great testament to what they have done.
"Clearly, they have raised their game and it is a very well-run club. They will, without a doubt, be a long-term player and a force to be reckoned with for many years.
"I think Manchester United have got to respond to that, as well as other clubs."
Source: PA
