Porto suffered their first league defeat in 54 matches on Saturday as they were beaten 1-0 by Academica at the Estadio Cidade de Coimbra.
The champions, who had last lost a league game in January 2012, have now gone three Primeira Liga matches without a win after succumbing to an Academica side who had won only three times in the top flight going into the game.
Fernando Alexandre was the hosts’ hero, registering his second goal of the season on the stroke of half-time to set his side on the way to a major shock – although they had to survive a second-half penalty scare.
The midfielder stole in at the far post and kept his cool to angle an effort into the roof of the net from close range after a delivery from the right was not cleared by the Porto defence.
Porto piled on the pressure in the second half but wasted a golden opportunity to restore parity when Ricardo saved a late Danilo penalty after Jackson Martinez went down in the area.
Paulo Fonseca’s men threw everything at Academica, sending goalkeeper Helton forward for a series of corners in the dying stages, but it was to no avail as the hosts made it three wins from their last four league matches.
Porto have now won only one of their last five games in all competitions ahead of their league clash with Sporting Braga on Saturday.