BBC Sport says Chelsea's summer market plans aren't over as they seek to add an attacking midfield signing before next week's summer market closes.
Fermin has attracted an approach from Manchester United this summer and now Chelsea are also keen.
However, any move from Chelsea will hinge on them making room in their wage ceiling with several major sales.
For his part, Fermin is reluctant to leave Barca, though the Catalans wish to sell as they also need to create room to meet LaLiga financial controls in order to register summer signings - which include Roony Bardghji.
Any move for Fermin will hinge on Chelsea failing to strike terms with Manchester United for Alejandro Garnacho or with RB Leipzig for Xavi Simons.
