Frank Lampard is searching for defensive reinforcements, with the left-back position thought to be a priority at Stamford Bridge.
Ben Chilwell is reportedly Lampard’s first choice, but Leicester’s £80million valuation is proving to be a sticking point.
Reguilon is the latest in a growing list of cheaper alternatives, according to Sky Sports.
Nicolas Tagliafico, Alex Telles, Robin Gosens and Marc Cucurella have all been linked with a move to Stamford Bridge.
Reguilon has enjoyed a standout season on loan at Sevilla from Real Madrid, helping them to a top-four finish in La Liga and Champions League qualification.
Madrid already have Marcelo and Ferland Mendy as options at left-back and need to raise funds to strengthen their squad elsewhere.
Everton have already bid £18m for the Real Madrid academy graduate but Chelsea have reportedly made their interest known and a larger bid is expected in the coming days.