Barcelona sporting director Robert Fernandez was reportedly in an attendance for Chelsea's 2-1 triumph over West Ham United at the London Stadium on Monday evening.
According to Marca, Fernandez and his chief scout watched the Premier League leaders in action as they prepare for a big spending spree this summer, with additions in defence and midfield a key priority.
The Spanish publication claims that defenders Cesar Azpilicueta and Marcos Alonso, as well as substitute Nemanja Matic, were of "particular attention" to Fernandez during the game.
Fernandez then went on to see Arsenal get hammered by Bayern Munich in the Champions League the following night, when the movements of right-back Hector Bellerin were thought to be on his radar.
Barcelona, who currently lead the way in La Liga by one point, will also be in the market for a new manager this summer after Luis Enrique announced his intention to step down.