Chelsea have placed a bid for Porto attacking left-back Alvaro Pereira, according to Sky Sports News.
The Blues have been credited with interest in several players from manager Andre Villas-Boas's former club, most recently Pereira and Joao Moutinho.
The club had reportedly been considering an offer of around €35m (£22m) for the 25-year-old Uruguayan international.
Pereira, who has been at the Portuguese club since 2009, is believed to have a €30m (£26m) release clause.