Patrice Evra fears Manchester City would become an unstoppable trophy-winning machine were they to snatch the Premier League title away from Old Trafford.
Manchester United remain the favourites to land a 20th top-flight crown this season, as they hold a three-point lead at the summit, but are aware that defeat in Monday's 'unmissable' derby date with City would hand the initiative to their arch-rivals.
Evra admits such a situation does not bear thinking about, with United desperate to avoid ending the season empty-handed.
The Red Devils are also wary of allowing the floodgates to open at the Etihad Stadium, with it possible that one title success would pave the way for City to emulate their own achievements during the Sir Alex Ferguson era.
Evra warned: "Beware. If City start winning it will be hard to stop them.
"We have to stop them before they start, because they can go far. That's how a big team starts, the first trophy they win.
"They won the FA Cup last year and if they win the league they'll get too much confidence.
"If they win the Premier League, a page is turned and it's a revolution, and revolutions have always been about Manchester United.
"If you play for Manchester United, if you're a leader or a captain, it's to play in a match like this. You have to accept your responsibility.
"Whether it's me, or someone like Ryan Giggs, if you ask them which title they will appreciate the most, it will be this one."
What will be the outcome in the match Man City vs Man Utd?