Porto are making a late attempt to trump Chelsea for Atletico Paranaense midfielder Nathan.
Nathan has spent the past three weeks in London finalising a move to Chelsea after successfully passing his medical.
However, no fee has yet been settled between the two clubs.
Gazeta do Povo says Porto, backed by management firm Doyen Sports, have made contact with Atletico PR with an offer of €5 million.
Mario Celso Petraglia, president of Atletico, was recently in Portugal to meet with clubs, including Porto.