Porto said in a statement that they had "decided to replace the coaching team led by Julen Lopetegui" after they followed up a defeat by rivals Sporting Lisbon on Jan. 2 with a 1-1 draw against Rio Ave on Wednesday.
Lopetegui, who joined Porto in 2014, also failed to steer the Portuguese side into the last 16 of this season's Champions League after they finished third in their group behind Chelsea and Dynamo Kiev.
The twice European champions are third in the Portuguese championship behind leaders Sporting and Benfica after 16 games.
The 49-year-old Spaniard failed to win a trophy in his time in charge at Porto and has been temporarily replaced by Rui Barros.
(Reporting by Toby Davis in London; editing by Ed Osmond)
