Pereira blasts 'horrible' Porto after cup exit
Porto lacked speed and incision up front and were also exposed at the back as they conceded three second-half goals by Marinho, Diogo Valente and Adrien.
"We put on a horrible display. The team simply did not exist today, we lacked aggression in attack and defence," said Pereira who took over in the close season when Andre Villas-Boas joined Chelsea having steered Porto to the league, cup and Europa League treble.
Pereira's team are also languishing in third place in Champions League Group G and desperately need a win when they travel to bottom club Shakhtar Donetsk on Wednesday.
Porto and arch rivals Benfica are level on 24 points from 10 matches at the top of the Portuguese championship.
Benfica progressed in the domestic cup by beating Naval 1-0 on Friday.