Porto have parted company with head coach Nuno Espirito Santo by mutual agreement.
The 27-time Portuguese champions confirmed the news in a brief statement on their official website on Monday.
Former Valencia boss Nuno, who enjoyed two spells with Porto during his playing career as goalkeeper, signed a two-year contract to succeed Jose Peseiro in June.
He improved upon their third-place finish from 2015-16, but Porto were still unable to prevent rivals Benfica claiming a fourth consecutive Primeira Liga title.
Porto finished six points off the pace in second, having faltered in the home stretch with a run of five draws and three wins before a 3-1 final-day loss at Moreirense.
Nuno led Porto to the last 16 of the Champions League, where they were knocked out by finalists Juventus.