Peter Kenyon says Chelsea are on their way to overtaking Manchester United as the world's biggest football club, ahead of their crunch game on Sunday.
Blues' chief executive Kenyon also said they will have to quit Stamford Bridge.
"By 2014 we want to be internationally recognised as the number one club," he said. "But I think it's pretty clear we can't get to where we want to here."
But United winger Cristiano Ronaldo hit back, saying Chelsea would fall apart if boss Jose Mourinho left the club.
He said: "Mourinho is a great coach and he is Portuguese, so I can't speak badly of him.
"I would like to see what would happen if he were to leave Chelsea. Perhaps they would stop getting good results."
United go into Sunday's Old Trafford showdown three points clear of champions Chelsea and Ronaldo believes that while United have improved from last season, the Blues have not moved forward.
"Chelsea are about the same as last year," added Ronaldo. "Andriy Shevchenko and Michael Ballack haven't changed them in terms of their superiority to everybody else.
"They have to work harder to win games and they only just do enough to win.
"The rivalry between us and Chelsea exists, but there isn't the same passion as the Manchester derby games or matches against Arsenal or Liverpool."
Kenyon, meanwhile, does not think Sunday's eagerly-anticipated contest will have any bearing on the outcome of this season's Premiership title.
"Sunday is not the deciding game, as much as we try to build it up," added Kenyon. "I think we still have a long way to go in the season.
"I think the team is the best team we've had in the three years I've been here.
"In depth, I think the squad is tremendous, and I don't actually think we've seen the best of Chelsea at this stage in the season."
United's Dutch goalkeeer Edwin van der Sar, however, reckons it is the biggest game of the season.
"It doesn't get much bigger than this," said Van der Sar.
"When we played them at home last season we were 10 points behind, now we are three ahead, so it goes without saying we are in a better position.
"I am sure everybody will put what happened against Celtic on Tuesday to the back of their minds and be ready to try and get the result we want against Chelsea."
