Joao Moutinho's 56th minute goal separated the two sides at Estadio do Dragao in a match which the home side dominated from a possession and attempts on goal viewpoint.
11 minutes into the second half, Moutinho got on the end of Alex Sandro's perfect cross to slide home with a first-time effort which edged the Portuguese side in front prior to the return bout on March 13.
Malaga will be confident about overturning the deficit at La Rosaleda after beating both Zenit St Petersburg and AC Milan there during the group stage but they will have to make all the running as the two-time European champions hold a one-goal advantage.
2012/13 UEFA Champions League - Round of 16 first leg
Estadio do Dragao, Porto - 42,209
Yellow cards:POR - nil MAL - Manuel Iturra 75'