By FOX Sports Staff
The two Premier League giants meet at Old Trafford this weekend in the sixth round of England's most famous cup competition.
The last time United played the Blues in the FA Cup was in the 2007 final which ended in extra-time heartbreak for the men in Red.
Adding to the motivation for United, Sunday's game comes immediately after being knocked out of the UEFA Champions League following Tuesday's controversial 2-1 defeat to Real Madrid in Manchester
"I felt we were very unlucky to lose the 2007 final," Ferguson told Inside United recently.
"Didier Drogba scored in [almost] the last minute of extra time after we had a very strong penalty shout turned down.
"I think Ryan Giggs may have forced the ball over the line as well for a goal that wasn't given. That was tough to take, but that's football - you win some, you lose some."
Interestingly, among the current United squad only Ryan Giggs, Paul Scholes and Darren Fletcher have an FA Cup winners' medal.
Summer signing Robin van Persie has won it as well but he earned it during his time at Arsenal in the 2005 final where the Gunners snatched a penalty shootout win over United despite being dominated.
"Don't remind me of that game," Ferguson said
"We annihilated Arsenal, it was like the Alamo. They had one shot and we had something like 23 shots on target."
Should United get past Chelsea, they will be drawn into the semi-final of the competition immediately after Sunday's encounter at Old Trafford.
United are looking to win the FA Cup for a record 12th time.