Porto president Nuno Pinto da Costa says they wasted the talent of Stoke City record signing Gianni Imbula.

Da Costa blames former coach Julen Lopetegui for Imbula's poor experience in Porto.

"Imbula came by his (Lopetegui's) will," he said.

"He told me he was a Ferrari. I later thought, he is a Ferrari and is parked in the garage?"

Da Costa has negotiated a super deal for Porto over Imbula's sale - a €24 million fee, plus 15 per cent from any future sale.