The Czech youngster made an impressive full debut in the memorable 2-0 win at Liverpool late on last season, but Jose Mourinho is desperate for him to play regular football to boost his development – something that he sees as not possible at Stamford Bridge.
January signing Kurt Zouma will make his long-awaited switch from Saint Etienne ahead of next season, but despite his billing as a top Ligue 1 defender, at 19 he is also seen as too inexperienced to make an instant impact.
As a result Mourinho is willing to once again dip into the transfer market, with Mangala, Benatia and Varane of Porto, Roma and Real Madrid respectively on his shortlist.
Even with the £40m fee coming in for David Luiz and Chelsea’s vast wealth, the Londoners can only afford one of the three, with the latter believed to be the top target.
Mourinho is known to be a massive fan of Varane after coaching him at Real, and even hailed him as one of the best defenders on the planet recently.
But with the Frenchman unlikely to be available, Mangala and Benatia – who have both been linked with Manchester City – are alternative options.
All three are valued at around £25m-£30m.