There's no doubt, Chelsea vs Manchester United means a lot more today than it did before Roman Abramovich took over the Stamford Bridge-based outfit.
The Blues' rise to the summit of English football almost certainly would not have been achieved so quickly without the Russian billionaire's investment and with each passing season, the rivalry between Chelsea and Man United does appear to grow in significance.
The fact Sunday's match at Stamford Bridge also marks the first return of Jose Mourinho to the club since being sacked last December adds another encapsulating storyline to the saga.
But of course, it wasn't always this way and ex-Red Devil Diego Forlan has revealed exactly what some of Man United's stars of the past used to think of Chelsea.
Forlan, who actually enjoyed most of his success after leaving Old Trafford in 2004, admitted he asked the captain at the time, Roy Keane what he thought of the Blues.
Keane remains as honest and outspoken now as a pundit as he was during his playing days and according to Forlan, didn't rate them too highly.
"'Chelsea are a small club, nothing like as big as Liverpool or Arsenal,' my captain Roy Keane and other Manchester United players explained when I asked them about Chelsea," Forlan told The National.
Wonder if Keane has the same opinion of Chelsea today? We'd guess not.
The former United captain was actually part of Mourinho's first Premier League game in charge of Sunday's opponents when he played in an unfamiliar centre-back role at Stamford Bridge in 2004.
On that day, Sir Alex Ferguson's men were defeated 1-0 by an Eidur Gudjohnsen goal.
Forlan was among the substitutes 12 years ago and he went on to praise the work Mourinho did at the Portuguese's former club.
He added: "In my time at United, Chelsea were bought by Roman Abramovich and would go on to become one of the strongest teams in the world. Jose Mourinho would also take charge just before I left England. He had become a hero there, taking a 'small club' and making them champions of England for the first time in 50 years.
"Mourinho is loved by Chelsea and can expect a good reception when he returns with his new club – United – on Sunday, even though he is trying to defeat the club who sacked him a year ago.
"Chelsea fans would probably prefer he was not at United. He achieved so much at Chelsea, winning the league in both of his spells there. That is why they will welcome him at Stamford Bridge, even though it is a game that neither he nor his Antonio Conte can afford to lose."
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