Sir Alex Ferguson has dismissed Peter Kenyon's claim that Chelsea are on track to overtake Manchester United as the biggest club in the world.
Ahead of Sunday's crunch meeting between the two clubs, Blues chief executive Kenyon said Chelsea are "more dynamic, more relevant" than United.
"It's a nice time to say that stuff," said United boss Ferguson.
"But I'm hardly going to tremble about it. How other teams look at these things is their business."
He added: "All I know is that we have a great history and have all these supporters because we entertain. We will not change from that."
Ferguson is hoping to extend United's lead over Chelsea with victory at Old Trafford.
"The match is a fantastic prospect. We have the possibility of going six points clear, which would mean them chasing us," he said.
"In the last two years Chelsea have been in the fantastic position of being nine, 10 points ahead of us and very difficult to peg back.
"It's a must-not-lose game for us"
"We have got out of the blocks this time and for the first time we are in front."
United go into the match three points clear of their London rivals after 13 matches, while at the same stage last season, they were seven points behind the eventual champions.
The match will be refereed by Howard Webb, who was picked ahead of Graham Poll to take charge of the potentially explosive match.
Ferguson said: "I hope it's not a game like we've seen recently. We don't want to see players crowding round referees.
"Howard Webb is a young referee and if he's fair no-one can complain."
Meanwhile, Chelsea midfielder Frank Lampard sought to play down the importance of the match in terms of the destination title.
"It's a must-not-lose game for us. Our intention is to win the game and if not then draw," he said.
"But even if we lose, there is a long way to go.
"I believe in us and the better team will be the one that wins the league. Win, lose or draw we have to keep looking at the bigger picture which is to win the league."