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Real Madrid are eyeing Everton centre-back John Stones as a potential replacement for Raphael Varane should the Frenchman make a move to Manchester United.

Real president Florentino Perez recently revealed that the Manchester outfit made enquiries about Varane in the summer transfer window, per Spanish radio station Cadena Ser (via Hamish Mackay in the Mirror).

With United's central defence far from settled they will likely return for Varane next summer, and should they be able to prise him away from the Bernabeu, Madrid will reportedly look to Stones as a replacement, per Spanish outlet AS (h/t Adam Skinner in the Express).

The La Liga giants will likely face huge competition from Chelsea, who are in need of added strength in defence—as proven by their poor start to the new season—and who were desperately disappointed not to sign Stones in the summer, per Bleacher Report's Sam Tighe:

Everton held firm against Chelsea's numerous offers, the latest of which was reported at £38 million, per Charlie Skillen and Elliott Bretland on MailOnline. 

With the 21-year-old contracted at Goodison until 2019, Everton will demand a similarly huge bid next summer if Real are to get their man.

Indeed, if Chelsea and Real end up going head-to-head for the Englishman's signature, Everton could potentially bring in over £40 million for Stones.

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It is far from guaranteed, though, that Real will need to bid for Stones as Varane could well stay on at the Bernabeu.

While he was used only sparingly by Carlo Ancelotti last season, he has started two of Madrid's three La Liga games so far this season under new boss Rafael Benitez, per WhoScored.com.

With stalwart Real centre-back Pepe now 32 and in the twilight of his career, 22-year-old Varane could surely be persuaded that his long-term future is as a first-team regular at Real.

However, with the Red Devils currently deploying an out-of-position Daley Blind as a makeshift centre-back—albeit relatively successfully thus far—they may come in with an offer too good to turn down for Varane and Madrid.

In such an event, Stones would be a worthy replacement. Both Stones and Varane are widely regarded as two of the best young centre-backs in the world, and both are relatively similar in their style as they like to play the ball out from the back.

Chelsea would be devastated should they end up losing out on Stones to Real, but United could kick off quite a scrap between Los Blancos and the Blues should they sign up Varane.