The 26-year-old started his professional career at Celta Vigo, making 166 appearances for the Sky Blues in all competitions, scoring 22 goals and registering 18 assists in the process.
Mendez made the move to Real Sociedad in the summer of 2022, and he has continued to impress for the Basque outfit, managing 16 goals and 13 assists in 62 appearances in all competitions.
Last season, the Spaniard scored 11 goals and registered eight assists in 47 appearances, while he has five goals and five assists in 15 outings this term.
Mendez still has five years left to run on his contract, having penned a six-year deal upon his arrival, but there is currently speculation surrounding his future due to his strong performances.
According to Fichajes, Barcelona are huge admirers of the midfielder and could make a move for him when the winter transfer window opens for business.
The report claims that Tottenham Hotspur have also shown an interest, but Barcelona are currently the team 'seriously considering making a bid' at the start of 2024.
Mendez has two goals and four assists in 12 La Liga appearances this season, while he has managed three goals and one assist in three Champions League appearances.
The four-time Spain international largely operates as a central midfielder for Real Sociedad, but he has also played off the right and through the middle during the 2023-24 campaign.
Barcelona are expected to sign at least one new central midfielder next year, with head coach Xavi currently short of experienced options in that area of the field.
Oriol Romeu was re-signed over the summer following the departure of the inspirational Sergio Busquets, while Ilkay Gundogan arrived on a free transfer from Manchester City ahead of the new season.
Frenkie de Jong is also expected to soon sign a new deal, while Fermin Lopez has also emerged as a first-team player this season.
Gavi, 19, and Pedri, 20, are regarded as two of the best young midfielders in world football, but the latter has had a number of injury problems early in his career, while the likes of Marc Casado, Unai Hernandez, Aleix Garrido and Angel Alarcon lack experience.
Xavi was highly critical of his side's performance against Shakhtar Donetsk in the Champions League on Tuesday night, with the Catalan outfit suffering a 1-0 defeat.