Bayern Munich's coach Pep Guardiola reacts during their Champions League quarterfinal first leg soccer match against Porto at Dragao stadium in Porto April 15, 2015. [Photo/Agencies]

The visitors were grateful to Neuer for pulling off a stunning fingertip save early in the second half to prevent Boateng scoring an own goal, before Porto took a well-deserved and potentially decisive 3-1 lead.

Bayern's dismal defending cost them again when Boateng failed to deal with a high ball and Martinez stole in to round Neuer and sidefoot home.

An increasingly fraught second half was littered with yellow cards and bookings for Porto's first-choice full backs Danilo and Alex Sandro ruled them out of the second leg in Munich.