Derby will demand £4m in compensation if Chelsea are to take Frank Lampard as their new manager - though there is a clause in his contract which allows him to move, Sky Sports News understands.
Chelsea are yet to make a formal approach, but Derby are bracing themselves for that to happen now an agreement has been reached for Maurizio Sarri to take over at Juventus.
Sky in Italy understand that, while Chelsea and Juventus have agreed the details of Sarri's move to Turin, he will not be confirmed until the Premier League club have finalised plans for his replacement, who they hope will be Lampard.
Sarri, who guided Chelsea to a third-place finish in the Premier League and a Europa League win, will complete a return to Italy after a single season in English football. Other managers have been linked with the role, but it is understood Lampard is now Chelsea's top choice to replace the outgoing Italian.
Massimiliano Allegri, who had been touted as a potential candidate for the role, announced on Thursday he is to take a year out of football after leaving Juventus.
Lampard still has two years on his existing contract, and it is understood while he would find it impossible to turn Chelsea down if an offer is made to him, he is also very respectful of Derby's fans and the club's owner, Mel Morris, who gave him his first chance as a manager.
Under the terms of his current deal, any club wishing to take him is required to pay £3.5m in compensation to Derby and that figure rises to £4m if the buying club is playing Champions League football, which Chelsea will be doing next season.
With negotiations and legal discussions yet to start, it is thought it may still take a week or more before Lampard could be introduced as the new Chelsea manager.
Lampard enjoyed an impressive debut season in management, leading Derby to the Championship play-off final where they lost 2-1 to Aston Villa.
Chelsea are facing the prospect of a two-window transfer ban but would be appointing two figures with a deep understanding of the club should Lampard return alongside his Derby assistant Jody Morris.
Lampard spent 13 years in west London, winning three Premier League titles, four FA Cups, two League Cups, the Europa League, and Champions League, becoming the club's all-time top goalscorer in the process.
Morris, who started his playing career at Chelsea, impressed as a youth coach at Stamford Bridge before leaving to join Lampard at Derby.
Both have an acute understanding of the club's youth setup and players who are out on loan, which could be vital given their impending transfer ban.
Chelsea have appealed against their two-window transfer ban imposed by FIFA to the Court of Arbitration for Sport.
If Chelsea appoint Lampard, he will be the first English manager to take charge of the club in 23 years.
Meanwhile, former Chelsea midfielder Claude Makelele has left his role as manager of Belgian side Eupen amid speculation he could be part of the new coaching team at Stamford Bridge.
Makelele, who played in the 2006 World Cup runner-up team, won two Premier League titles at Chelsea after joining from Real Madrid in 2003. His time at the club ended after the 2008 Champions League final loss to Manchester United.
Makelele's former team-mate Petr Cech is expected to be announced as Chelsea's sporting director, with Lampard possibly returning to replace Sarri as coach.
'Lampard perfect for Chelsea'
Meanwhile, Jamie Redknapp believes Lampard would be the "perfect person" to replace Sarri as Chelsea manager.
Lampard has been linked to the managerial job at Chelsea following his successful first season at Derby where he lost to Aston Villa in the Championship play-off final in May, and Redknapp feels he would be a good fit at Stamford Bridge.
Speaking at Stamford Bridge ahead of Soccer Aid for Unicef, Redknapp told Sky Sports News: "Frank would be the perfect person. Sarri is still the manager right now so until that changes, if it were to change and if they need a manager next year, they need someone who's going to come in and stabilise the club.
"They have lost their best player [Eden Hazard] and they have got a transfer embargo for two or three windows, so you need someone that everybody loves and they will give them time."
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