Porto have parted company with head coach Julen Lopetegui after faltering in the Primeira Liga title race.
Lopetegui led Porto to second in Portugal's top flight behind Benfica in 2014-15 - his first season in charge at Estadio do Dragao - and his hopes of going one better this time around were severely hit over the past week.
Current leaders Sporting CP condemned Porto to their first loss in the league for almost a year on Saturday, Islam Slimani netting a brace, and Wednesday's 1-1 draw at home to Rio Ave left them four points off the pace.
The club's board decided to take action with Porto third behind Benfica on goal difference, while losses at home to Dynamo Kiev and away at Chelsea saw them eliminated from the Champions League at the group stage.
Porto also confirmed that assistant coach Rui Barros will take charge in the interim, with a statement reading: "The management of FC Porto - Futebol, SAD has decided to replace the technical team led by Julen Lopetegui.
"In this regard, the workout on Friday will be guided by Rui Barros, who temporarily assumed the technical management of the professional football team.
"FC Porto and Julen Lopetegui are currently negotiating the terms of the contract termination."
Porto will now begin the process of searching for a new head coach, with former Valencia coach Nuno Espirito Santo thought to be the front runner for the vacancy.
Porto travel to Boavista on Sunday and resume their European campaign with a mouth-watering Europa League tie against Borussia Dortmund in February.