Azpilicueta has been linked with the European champions virtually all year and reports in France have claimed an agreement was reached over a transfer fee late Tuesday night.
It was also suggested the 22-year-old Spaniard, who started Marseille's opening two Ligue 1 games of the season, would sign a five-year deal at Stamford Bridge.
The fee was said to be undisclosed but it has been reported to be in the region of ?7million.
Chelsea stuck to their usual policy of not commenting on transfer speculation on Wednesday morning.
Source: PA
Source: PA