Porto continued their unbeaten run, while Edinho bagged a hat-trick as Academica overcame Vitoria Setubal in Liga Sagres on Saturday.
Jackson Martinez's 25th-minute goal handed Porto a 1-0 victory at home to Nacional, who slipped to 14th on the table and just one place above the relegation zone.
Porto remained second on the table with 10 wins and two draws in 12 matches, behind leaders Benfica on goal difference.
Meanwhile, three goals from Edinho guided Academica out of the drop zone with a 4-2 win at home to Vitoria Setubal.
Salim Cisse opened the scoring for Academica in the 12th minute before Edinho doubled the advantage three minutes later.
Academica seemed in control of the contest when Edinho struck again on 27 minutes, but the visitors roared back with second-half goals from Cristiano and Albert Meyong.
Setubal fought gallantly in search of an equaliser but came undone as Edinho put the result beyond doubt with six minutes to go.
Academica jumped from 15th to ninth on the table, while Vitoria Setubal slipped to 15th place on the back of their third straight loss.
Elsewhere, Pacos de Ferreira accounted for Sporting CP 1-0, while nine-man Olhanense held on against Rio Ave by the same score.
Gil Vicente drew 0-0 with Vitoria Guimaraes.