The Madeiran club had a night to forget with goals from Ivan Marcano and Toni Martinez making it five goals without reply.
Claudio Winck scored a late consolation in the dying minutes of a match that Vasco Seabra and his team will want to forget as soon as possible.
Maritimo started strong with Bruno Xadas unleashing a long-range strike that just went off the top of the bar. The visitors had the first three corners of the match, maintaining the pressure against their more fancied opponents.
Maritimo should have taken the lead in the 9th minute as Ivan Marcano’s weak back pass was pounced on by Joel Tagueu, but Diogo Costa was alert to the danger and produced an important save.
It proved a costly miss with Porto gifted the opening goal three minutes later.
Claudio Winck’s heavy touch allowed Zaidu Sanusi to steal the ball which fell to Evanilson, he rolled it out to an unmarked Mehdi Taremi who gracefully slotted it past Miguel Silva.
Tageu produced a late challenge on Pepe in the 28th minute which saw him booked alongside Mateus Uribe for overzealously protesting.
Sanusi was creating all sorts of problems down the left wing, beating Winck and creating a chance for Pepe Aquino that he fired over the bar.
Porto then doubled their lead in the 40th minute with a beautiful goal as Mateus Uribe’s long ball over the defence found Joao Mario whose first time cross picked out Evanilson who took a touch and found the net.
Two minutes later the contest was over as a horror pass from Stefano Beltrame saw the ball fall straight to Danny Loader, who had his shot saved only for Taremi to be on hand to accept another gift.
Conceicao made a triple switch in the 68th minute with Mateus Uribe, Danny Loader and Evanilson making way for Stephen Eustaquio, Galeno and Toni Martínez. Less than a minute later it was 4-0 thanks to Ivan Marcano.
Toni Martinez round the game for Porto 11 minutes later, before Winck Claudio pulled one back for Maritimo.