The 23-year-old enjoyed a successful loan spell with Sevilla last season, helping them win the Europa League.
His form for the Andalusian club has led to interest and Manchester United have made him an ‘attractive offer’.
Reguilon is hesitating over that option because he still hopes to play for the ‘club of his life’ Real Madrid.
Madrid have two established left-backs – Ferland Mendy and Marcelo – but Marcelo turns 33 next year and there could soon be a place for Reguilon.
United are offering a four-year deal, but accepting their proposal would make a return to Madrid difficult for Reguilon.
AS reports that the Sevilla option ‘is growing in his head’ as it would keep his Madrid dream alive.
Sevilla sporting director Monchi and coach Julen Lopetegui are pushing for a loan renewal without the option to buy.
United are willing to pay €30m for Reguilon, an offer Madrid would be inclined to accept.