Andre Villas-Boas has indicated his intention of beefing up the Blues defence in the January transfer window.
Bolton defender Gary Cahill's move to Stamford Bridge is poised to be completed over the coming weeks despite initial disagreements with personal terms.
But the Portuguese coach has planned further defensive reinforcement in the form of Azpilicueta.
The Spain Under-21 international has impressed for Marseille this season and has attracted interest from around Europe.
However, the French Ligue 1 side are reportedly demanding a hefty €14.5million for the 22-year-old - a price that the Blues may not be willing to pay considering his lack of experience and physical strength.