Chelsea are leading the race for Spanish full-back Sergio Reguilon with Serie A side Napoli also interested, according to reports.
The Blues have spent heavily in the attacking areas so far this window.
Deals for Timo Werner and Hakim Ziyech were completed, while Bayer Leverkusen playmaker Kai Havertz remains a top priority.
Tension between Frank Lampard and Roman Abramovich could be rising over their failed efforts to land the German thus far, but Chelsea remain steadfast in their pursuit.
Elsewhere, rumours of defensive additions have also circulated.
With a Premier League defence that conceded the most goals (54) in the top half last season, Chelsea’s defence could be set for strengthening.
Leicester left-back Ben Chilwell has emerged as one target, though his £80m valuation could prove a difficult hurdle to overcome.