A home win over Wigan Athletic on Sunday will secure the Premier League after a three-year drought and the Londoners will start as huge favourites in the FA Cup final against Portsmouth six days later.
Russian multi-billionaire owner Roman Abramovich will no doubt greet a first double with his usual understated grin.
Yet when he sits down to watch Chelsea's Champions League conquerors Inter Milan take on Bayern Munich in the final on May 22, Abramovich will surely wonder what might have been if Jose Mourinho - who is eyeing a treble with Inter - had stayed as boss at Stamford Bridge.
When Ancelotti arrived last year his brief was clear - bring home the ultimate club trophy in global football to west London for the first time. He was an obvious choice for the task having won it twice at AC Milan in 2003 and 2007.
An outwardly calm, avuncular figure, Ancelotti settled in well from the start though his interviews carried out in limited English generally shed little light on his ideas.
Not the obsessive, cagey tactician like the self-styled "special one" Mourinho, nor did he sink to the Arsene Wenger routine of apparently blaming others when Arsenal lost.
REMAINED CALM
Similarly he stayed calm when things were going well and he remained steadfastly above the "mind games" of Alex Ferguson which had successfully psyched out other title-contending managers.
Not that Ancelotti is afraid of giving his players a dressing down when he thinks standards are dropping as they found at halftime in their FA Cup fifth round game against Cardiff this season.
"The manager was crazy, so we went into the second half knowing what we had to do. He went mad at us," said midfielder John Obi Mikel as Chelsea kicked on from a 1-1 halftime scoreline to win 4-1.
"He shouted at us in English and Italian, everything. When he's mad he mixes everything up. He was not happy. Normally, he's pretty laid back. But when things are not going right, that's when he goes a bit mad."
The fans and the media's view remains, however, firmly restricted to a far more sober, almost party-pooping, kind of character.
When Chelsea fans sang at one recent game "Carlo, Carlo give us a wave", it needed the intervention of assistant and Chelsea long-termer Ray Wilkins to make him aware of the call, to which he eventually responded with a sheepish flap of the arm.
He has shown faith in his players, and as at Milan, his approach has been to respect the knowledge and experience of his senior pros.
He dealt well with the absence of key players during the African Cup of Nations and took confidence from how the team performed without Didier Drogba to become more adventurous in his tactics in the latter half of the season.
As a result the goals have rained in from all angles and, with Nicolas Anelka sometimes alone up front, the midfield have been even more productive and difficult to play against.
Three times this season Chelsea have score
