The latter Belgium international was outstanding for the Blues during their Premier League title-winning season last term and has emerged a target of Real Madrid's.
Chelsea's dramatic turn in fortunes this time around has led to widespread reports that Courtois is unsure on his future at Stamford Bridge and would be interested in a return to Spain, where he enjoyed two seasons on loan with Atletico Madrid.
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And it appears the west Londoners are fully aware of the uncertainty surrounding their Belgian shot-stopper and have begun planning for life without him, with 17-year-old wonderkid Donnarumma at the top of their wish list.
Despite only having made 22 Serie A appearances throughout is short career, the Italian is attracting considerable interest from across Europe; Real Madrid, Atletico and Manchester United have all been previously linked with him.
Standing at 6" 5' tall, the towering teen has thoroughly impressed with a number of eye-catching performances for the Rossoneri, prompting comparisons with Juventus and Italy 'keeper Gianluigi Buffon.
Should Chelsea declare official interest in Donnarumma and plot a summer move, what's certain is they would have to pay big to secure his signature.
As recently as November, the youngster's agent, Mino Raiola, claimed his client was worth £120 million - not far short of double Chelsea's £73 million valuation of 23-year-old Courtois.
However, it's likely Milan would settle for far less, with Chelsea reportedly willing to offer up to £30 million.
Donnarumma became the youngest ever player in Italian football to make a top-flight appearance earlier this season, making his debut aged just 16 years and eight months.