The home team are third last in 16th place with 13 points and lost 2-1 against Rio Ave on December 29, while Porto are in second place with 40 points but are level on points with Sporting after their 4-0 victory against Boavista on December 28.
Match preview
The hosts and Rio Ave both produced three big chances in their clash last Sunday but Rio Ave created 2.05 xG, considerably more than Nacional's figure of 0.63 xG.
The defeat means that Nacional occupy the league's relegation playoff spot and are only one point ahead of the two automatic relegation spots at the bottom of the division, but they are level on points, goal difference, goals scored and goals conceded with 15th-placed Farense.
Manager Tiago Margarido will be concerned that his team's return of 11 goals scored in the top flight only betters the numbers posted by two clubs, though his side's record of 23 goals conceded is the league's joint ninth best tally.
The Nationalists are in poor form having lost four, drawn two and won just two of their eight most recent outings, and have in fact been defeated in nine of their past 14 games.
Margarido's side have at least proven difficult to beat at home, with the club winning three and drawing one of their seven matches at Estadio da Madeira, and it should be noted that two of their three defeats have come against giants Sporting Lisbon and Benfica.
Opponents Porto thoroughly outclassed Boavista on Saturday given they produced seven big chances while preventing Boavista from creating a single one themselves.
Head coach Vitor Bruno will be delighted that his side have so far managed to take advantage of the fact Sporting have dropped eight points in their last five league matches, with his team picking up 13 points in that time.
The Dragons have been outstanding at both ends of the pitch, with the title hopefuls scoring 40 goals and conceding just nine times in the league, and these are the top flight's second best offensive and joint best defensive records.
While the visitors have only failed to win three of their last seven away matches in the league, they have lost three, drawn two and triumphed in just one of their six most recent games on the road in all competitions.
Porto's record against Friday's hosts is impressive considering they have emerged victorious in 18 of their 22 clashes, with Nacional's last win coming in March 2014.
Nacional Primeira Liga form:
D
L
W
L
D
L
Porto Primeira Liga form:
L
W
D
W
W
W
Porto form (all competitions):
W
D
W
W
W
W
Team News
The home team could be forced to start Rui Encarnacao in goal due to Lucas Franca's injury last time out.
Encarnacao may be protected by a back four consisting of Gustavo Garcia, Ulisses, Leo Santos and Jose Gomes.
Djibril Soumare and Luis Esteves are probable candidates to start together at the base of midfield, while attacking midfielder Bruno Costa is likely to support striker Isaac.
Porto will be without midfielder Nico Gonzalez, who is suspended, as well as Marko Grujic due to injury.
Vasco Sousa and Stephen Eustaquio could feature in a double pivot behind attacking midfielder Rodrigo Mora.
Left-backs Francisco Moura and Wendell have both been ruled out, so expect Wenderson Galeno to play in a back four alongside Martim Fernandes, Nehuen Perez and Otavio.
Nacional possible starting lineup:
Encarnacao; Garcia, Ulisses, Santos, Gomes; Soumare, Esteves; Aurelio, Costa, Dudu; Isaac
Porto possible starting lineup:
Costa; Fernandes, Perez, Otavio, Galeno; Sousa, Eustaquio; Vieira, Mora, Pepe; Aghehowa
We say: Nacional 0-2 Porto
Porto have been rampant in the league this season and it is difficult to see how Nacional hold out against the visitors' strong attack.
Written by
Lewis Nolan