With Napoli and Tottenham Hotspur also reportedly interested in securing Aké's services - the former reportedly lining him up as a replacement for Kalidou Koulibaly - the Blues may be tempted to exercise their buy-back option on the Dutch international.
He spent six years at Stamford Bridge, but was left frustrated by a lack of first-team opportunities.
The versatile defender was sent out on loan three times during his time in west London, to Reading, Watford and current club Bournemouth, where he signed a permanent contract in July 2017.
Any deal for the 24-year-old hinges on Chelsea's appeal on their one-year transfer ban for breaching rules regarding the signing of youth players.
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