Porto on Thursday activated a 20-million-euro clause to make midfielder Oliver Torres's loan move from Atletico Madrid permanent in the second biggest deal in the history of the Portuguese league.

The 22-year-old Spaniard's move is just two million euros shy of the record transfer of €22 million that Benfica paid Atletico for Mexican international Raul Jimenez in 2015.

Porto coach Nuno Espirito Santo has started Torres in 27 matches this season.