The Blackburn boss will pit his wits against Ancelotti at Ewood Parktomorrow with the Blues needing victory to keep up the pressure on Arsenal and Manchester United.
Happier times: Jose Mourinho and Roman Abramovich before the split
Chelsea suffered a massive disappointment in midweek, going out of the Champions League to Mourinho's Inter Milan side, but Allardyce does not believe they are missing the Special One.
Allardyce said: 'He was on his way out, he had lost it and it appeared he had fallen out with the chairman and that change had to be made.
'He was no longer the manager he was when he first came because of whatever had happened behind the scenes.
'Perhaps he can't stay at a club for too long, like most foreign coaches, who are generally brought in to coach teams for one or two years and then move on.
'They are not long-term generally and perhaps that's what Jose needs, he gets two or three years, he's very, very successful and then he needs a fresh challenge.
'That's the way he lives his life and he's been outstandingly successful but when he left it was the right time for both him and Chelsea.
'Carlo Ancelotti could win the double still - and it's up to his players to prove that they can.'
Shouting the odds: Blackburn Rovers manager Sam Allardyce
Allardyce said Rovers needed to pull out the type of performance that saw them beat Aston Villa 2-1 in September despite being reduced to 10 men.
He added: 'You always want to play well against the big boys and enjoy the adulation if you beat them.
'This season we have done the bread and butter stuff very well and our success has mainly been against sides below us.
'We did manage to beat Aston Villa with 10 men which was an outstanding result.'
Allardyce has taken some tips from Mourinho's book of tactics by studying the success of Inter Milan but also studied Wigan's victory earlier in the season.
He said: 'We've also looked at what Wigan did when they beat them, as they are a team very similar to ourselves.
'We have to be right tactically and we need 11 lads prepared to roll their sleeves up and work harder and run longer than they have done all season.'
Allardyce does have a number of injury problems to cope with however with keeper Paul Robinson likely to be out for a month after sustaining a calf injury.
Jason Brown will fill in for Robinson with Mark Bunn being recalled from Sheffield United as cover but skipper Ryan Nelsen (knee), Gael Givet (groin), Lars Jacobsen (hernia) and Vince Grella (calf) are all missing while loan striker Franco di Santo cannot play against his parent club.
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