Jose Mourinho's appointment as Manchester United manager provides many talking points. Inevitably there are questions about the future of Juan Mata, who Mourinho sold to David Moyes at United in January 2014.
Despite being named Chelsea's Player of the Year in successive seasons, Mourinho was swiftly on Mata's case, suggesting the Spain international did not play football the way he wanted it to be played.
Mata was sold for £37.1 million, a record fee at the time for United and a transfer possibly borne out of desperation from the Old Trafford board to try and kick-start Moyes' career there.
Chelsea supporters queried the wisdom of the move. Mata, after all, had provided assists for telling goals in the 2012 FA Cup and Champions League final triumphs as well as the 2013 Europa League final victory.
He was viewed by Blues fans as "proper Chels," -- a colloquialism afforded to a select band of players who clearly understand that it is a privilege to play for the club and reflect this in the way they interact with supporters.
The size of the fee received and Chelsea's charge to the Premier League title the following season eventually negated supporters' angst. However, when Mourinho's Stamford Bridge world started to unravel in autumn last year and the team started underperforming, the short-term-gain-long-term-pain aspect of his methodology was put under the microscope.
In addition to Mata's departure and irrespective of the transfer fees involved, the sale of "proper Chels" centre-back David Luiz to Paris Saint-Germain and the subsequent form of Kevin De Bruyne and Romelu Lukaku -- two more sold by Mourinho -- raised suspicion the self-proclaimed Special One might not be that special after all.
What the future holds for Mata at Manchester United with Mourinho at the helm is open to conjecture. At 28, the man who scored in United's 2-1 FA Cup triumph over Crystal Palace is at the peak of his powers and many Chelsea fans would love see him back.
Whether or not incoming manager Antonio Conte holds Mata in the same high regard is unknown. If a deal were to be done to bring the Spaniard "home" it would have ramifications for Chelsea's current creative midfield players, one of whom would have to drop out of Conte's preferred starting XI.
It seems strange given his appalling form last season that Oscar was the player Mourinho originally backed in the coveted No.10 role at Chelsea ahead of Mata, and it would be astonishing if United tabled an exchange bid involving the Brazilian. If there is a deal to be done involving Mata, then Willian is more likely to be the primary factor in any transfer equation.
Willian was a model of indefatigable consistency for Chelsea amid a shocking season elsewhere, turning up week-in-week-out when many of his teammates failed to show up. An 11-goal haul and a samba-style flair with free-kicks make the Brazil international an enticing proposition for Mourinho and United. Reports indicate a valuation of £60 million for the 27-year old.
"Jose is one of the most successful coaches in the world and Manchester United will be stronger with him as manager," gushed Chelsea's reigning Player of the Year ahead of Brazil's Copa America campaign. "I played some of my best football under Mourinho. He is a special coach and I have a great relationship with him."
Clearly, Conte would be foolish to strengthen Mourinho's hand and weaken his own by approving the sale of Willian to United in a straight cash deal. Indeed, it's hard to see Abramovich sanctioning such a move given the giddy examples of Luiz, De Bruyne and Lukaku -- players lost to Chelsea at Mourinho's behest who now would be part of the core of the first team were they still at the Bridge.
Mata, plus £35 or £40m for Willian, would be a far more enticing proposition for Abramovich and Conte to consider as the funds could readily be used to strengthen the squad in other positions. With Chelsea holding the ace card in any future negotiation with United, it will be interesting to see if it is Mata the magician or Willian the workhorse who proves their value the most, should a deal materialise.