A goal in the 56th minute by midfielder Joao Moutinho was enough to give Porto a 1-0 win over visiting Malaga in the first leg of their confrontation in the Champions League knockout stage.
It was the Spanish club's first defeat in the 2012-2013 Champions League tourney.
Porto dominated in every phase of the game against a timid Malaga side.
Led by Portuguese international Moutinho and Brazil's Fernando Reges, the home team kept the visitors bottled up in their own end for minutes at a time.
Even after Porto scored, Malaga continued to sputter on offense, failing to establish the control of the ball that has been their trademark.
Bayern Munich inflicted a 3-1 home loss on Arsenal in Tuesday's other Champions League match.
Toni Kroos' goal at the 7-minute mark stunned the Gunners, who went into the match confident that their individual virtuosity could trump Bayern's system.
The visitors made it 2-0 with a strike by Thomas Müller in the 21st minute, but former Bayern Munich forward and German international Lukas Podolski cut the lead in half with his tally 10 minutes into the second half.
While the goal invigorated Arsenal, a strike by Mandzukic in the 77th minute crushed any hopes of a comeback. EFE