While it will be framed in terms of Fernando Torres and Didier Drogba, the record signing and the displaced icon, Carlo Ancelotti faces a choice tonight: to revisit his past or Chelsea's.
Ancelotti is thinking back to old styles to move Chelsea forward
Saturday's 1-0 win over Wigan Athletic was a microcosm of the systemic decision he has to make: he began with the 4-3-3 the club has trademarked since Jose Mourinho's appointment and ended playing 4-4-2, enabling the reconfigured Blues to resemble (in shape, if not success) the finest team Ancelotti played in and the first top-flight side he managed.
There was a time, long before he deployed a Christmas tree formation as AC Milan manager, when Ancelotti was a byword for 4-4-2.
Arrigo Sacchi's disciple helped anchor the midfield in his AC Milan side who exerted a revolutionary impact in Serie A and the European Cup in the early years of Sir Alex Ferguson's reign at Old Trafford.
Deploying the same system, he led Parma to second place in Italy in his second managerial job.
It seems to suit neither Drogba nor Frank Lampard, in particular, at a club where the current crop of wide players are not out-and-out wingers and it backfired in last week's Champions League defeat.
Yet when Chelsea overran United in the Premier League at Stamford Bridge last month, their high-energy approach seemed to vindicate Ancelotti's mentor.
Sacchi, who signed Ancelotti for AC Milan and appointed him his assistant when in charge of the Italian national team, said: "Pressing is not about running and it's not about working hard. I wanted my players to feel strong and the opponents to feel weak. Our pressing was psychological as much as physical."
This is not the counter-attacking that became second nature to Chelsea since Mourinho's arrival, or indeed the all-out attack with which Ancelotti's side ended last season.
This was something else altogether, an old-fashioned English approach allied with scientific planning, clear thinking and a high work ethic.
Yet for seven years, Chelsea's default method was to play Drogba alone up front, with support coming from the flanks and the marauding Lampard.
The recruitment of Torres brought the revival of the strike partnership, even though Ancelotti has been struggling to perm two from four forwards.
In the past, it was clearer: the nonpareils Ruud Gullit and Marco van Basten spearheading Milan's challenge, while Hernan Crespo and Enrico Chiesa were in the Parma forward line. Ancelotti adopted Sacchi's system with the enthusiasm of a zealot.
At Parma, in a decision he subsequently regretted, he opted not to sign Roberto Baggio, the 1993 World Player of the Year.
"He wanted a regular starting position and he even wanted to play behind the strikers, in a role that didn't exist in 4-4-2," Ancelotti recounted in his autobiography. "I wasn't willing to change my formation and told him so. I was wrong to be intransigent."
His inflexibility brought an indirect benefit for his current employers: another fantasista, Gianfranco Zola, was exiled, first to the left of midfield and then to Stamford Bridge, where he was to be voted Chelsea's greatest player.
"If I had a time machine, I'd go back and take Baggio," Ancelotti said.
"I was branded a coach who was opposed to attacking midfielders and that wasn't entirely unfair. Ancelotti, the anti-imagination: give me anything but another No 10.
"The truth is I was afraid of moving into a new territory that I knew too little about, but I made up for it in the years that followed."
It is an understatement; if Ancelotti the manager is associated with one brand of player, it is the free thinker.
At Milan alone, they included Rivaldo, Ronaldinho, Rui Costa, Clarence Seedorf and, the best of all, Kaka.
An initial suggestion to Roman Abramovich when they first met was that Chelsea should sign Franck Ribery.
The turning point, however, was when Ancelotti went to Juventus and, he realised: "I really couldn't bench Zinedine Zidane."
Given Abramovich's fondness for flair and the suspicion that a high-class creator may be part of the remodelling of Chelsea, 4-4-2 might not become as entrenched an idea with Ancelotti as it did during his playing days.
But, 22 years after he first conquered Europe with a systemic superiority, the Italian has to decide if going backwards will enable his team to take a seismic step forwards in the Champions League.
10.45pm, Aljazeera Sport +3