Should City take maximum points from their trip to Wolverhampton Wanderers later today, leaders United will travel to the Etihad Stadium with a three-point advantage over their neighbours.
Speaking after his side were held to a 4-4 draw by Everton this afternoon, Ferguson described next Monday's meeting as "the most important derby game" since he became manager of the Red Devils.
"We've got to get a result at Etihad Stadium now, it's a derby of amazing proportion and probably the most important derby game in my time," Ferguson told BBC Sport.
"We have to go there, perform in right way and not give away goals."
City beat United 6-1 earlier in the season, while United won 3-2 during an FA Cup tie at the Etihad in January.