Porto beat Beira Mar 3-0 to ensure they would end the second round of matches in the Liga alongside Nacional as the only teams with 100% records.
Falcao struck after 26 minutes to give Porto the lead, which they doubled on the stroke of half-time through Fernando Belluschi. Falcao grabbed his second to round off the scoring nine minutes from time.
Sporting left it late to claim their first win of the season, an 89th-minute penalty from substitute Matias Fernandez giving them a 1-0 victory over Maritimo.
Nicolas Godemeche's strike saw Naval beat Portimonense 1-0, despite having Carlitos sent off 15 minutes from time and Sunday's other game, between Uniao Leiria and Pacos Ferreira, finished goalless.
Reigning champions Benfica are still waiting for their first points of the new Portuguese Liga season after they were beaten 2-1 at Nacional on Saturday.
Jorge Jesus' side lost their opener last weekend and remain pointless after second-half goals from Luis Alberto and Carlos Orlando Sa sent Nacional to the top of the table with two wins from as many games. Substitute Jorge Carlos Martins scored a 90th-minute consolation for the champions.
In Saturday's other match, Vitoria Setubal held out for a goalless home draw with Braga.