Willian will reportedly leave Chelsea to join Barcelona at the end of the 2019-20 campaign.
The Brazil international has been a regular for the Blues this season but will see his contract at Stamford Bridge expire at the end of June.
Barca were linked with a £20m move for the 31-year-old in the latter stages of the January transfer window but were unable to get a deal over the line.
According to Marca, though, the South American is expected to move to Camp Nou on a free transfer ahead of the 2020-21 season.
Willian has contributed five goals and five assists in 30 appearances for Chelsea during the current campaign.
Barca were linked with a number of attackers in the latter stages of the January window with Luis Suarez and Ousmane Dembele both on the sidelines but were unable to get a deal over the line.