The Gunners negotiated the 2003-04 Premier League season without defeat, an achievement previously only performed by Preston in the 1880s
Just like Chelsea's one-in-a-generation 6-0 defeat of the Gunners in March - in Wenger's 1,000th game in charge - Mourinho believes it is not something which will happen in the modern Premier League era
"It's something that happened once in a lifetime," Mourinho said
"I don't see, in modern football with the competitiveness of this Premier League, one team being champion without a defeat
"That will stay in the history as the second and the last time
(That is) my opinion, but we don't know."
Chelsea have won five and drawn one of their six Premier League games so far this season and face a Gunners side also unbeaten
Arsenal capitulated on their last visit to Stamford Bridge, a match remembered for the gaping defensive holes as well as referee Andre Marriner's mistake in sending off Kieran Gibbs for a handball committed by Alex Oxlade-Chamberlain
Mourinho anticipates a much sterner test of his side, which features former Arsenal captain Cesc Fabregas pulling the strings in midfield
Fabregas was a precocious teenager when Arsenal won the 2004 title
"They will always be a difficult opponent," the Blues boss added
Mourinho loves the intensity of a derby day and testing himself against the best
His players will also need no additional motivation, just a few instructions
"I like it difficult," he said
"I like to play against the best
My players also like it
"Sometimes we are worried about the focus and we are worried about the approach
"When you play big matches you know the players are more than ready for that
"I have a meeting with them, but not a motivational meeting
Just a meeting to try to analyse a few things, a few images
"Just about football
Never about the emotional side of it, or the motivational side of it."
Arsenal manager Arsene Wenger has told his team that posing their own attacking threat at Stamford Bridge will be just as important as keeping "killer" Chelsea striker Diego Costa quiet on Sunday
The Gunners head across to west London on the back of an impressive 4-1 route of Galatasaray in the Champions League, as they look to make last season's 6-0 thrashing in Wenger's 1,000th match a distant memory
Spain international Costa has scored eight goals in six Barclays Premier League appearances since his £32million summer move from Atletico Madrid, but Wenger insists Arsenal - spearheaded by Danny Welbeck, who netted a European hat-trick in midweek - can offer plenty of forward threat themselves
"You have to find a balance between nullifying their strengths, but without forgetting to express your strengths," he said
"It is very important that we focus and concentrate on us having a great determination, a great desire and a great hunger to have a great performance, and focus on our performance and the way we want to play."
Wenger has long been an admirer of Costa, and is impressed by the way the Brazil-born forward has settled so quickly into the English game.
"He has done fantastically well," the Frenchman said.
"He has all the aspects of a striker that you like - he is focused, always determined and ready for a fight.
"He has also got players who can feed him like (Cesc) Fabregas and Eden Hazard, who can find him with final balls.
"Costa is a very efficient player
The timing of his runs and his determination, his killing determination - you feel he is a killer, he has that in him (when in front of goal)."
Despite having plenty of praise for Costa, Wenger is convinced the best is yet to come from Welbeck, signed in a £16million deal from Manchester United on deadline day.
"Danny is 23 years old
The fact that he plays regularly in the Premier League now, in his (central) position, means he is improving game by game, is adding to his game and that is very positive," Wenger said.
"There is a lot more to come from him, especially because he has the basics.
"Danny has a good technique, he has good pace and a good mentality, so I believe that Diego Costa is a good example for him to follow."
Arsenal would be nine points behind leaders Chelsea should they lose on Sunday.
Wenger, though, is not about to read too much into how the early Premier League table is shaping up.
"We want to go to Chelsea to win and, of course, they are six points ahead of us, (which) makes our desire even bigger," he said.
"They have started very well, but we have a big opportunity.
"We are (the only) two unbeaten teams in the Premier League
They have been more efficient in finishing their games off than we have been.
"We have had a bit more of a difficult run until now than they had because we played Everton, Manchester City and Tottenham in our games, but it is a vital game for us to stay in the race, of course."
Source : PA