Nacional sprung a surprise in the Liga Sagres on Saturday, beating Braga 3-2 at home, as Vitoria Guimaraes and Maritimo drew.
Braga had led going into the half-time break at Estadio da Madeira through Helder Barbosa's 37th-minute strike.
Nacional's comeback began when Edson Andre Sitoe equalised on 58 minutes.
Just two minutes later and Diego Barcelos struck to earn the home side the lead, before Ismaily's own-goal completed the unexpected turnaround.
Eder got one back for Braga on 83 minutes, but their hopes of forcing an equaliser suffered a blow when Hugo Viana was given his marching orders just 60 seconds after the restart.
Nacional's win saw them climb to eighth on the table, while third-placed Braga missed a chance to close on top two Benfica and Porto, who meet on Sunday.
In the other match on Saturday, Amido Balde's 95th-minute equaliser helped Guimaraes record a 1-1 draw at home to 10-man Maritimo.