The hosts and top-flight leaders were beaten by Braga last time out, while the visitors lost against Casa Pia and have suffered defeat in four of their last five away games in all competitions.
Match preview
Benfica suffered their first Primeira Liga defeat of the season when they were beaten 3-0 away against Braga last Friday.
Despite dominating possession, the Eagles failed to take their chances in front of goal, and strikes from Abel Ruiz and Ricardo Horta (2) ultimately helped Braga secure an impressive win against the 37-time top-flight champions.
Roger Schmidt's side remain at the top of the table after 14 matches played, but the gap to second-placed Porto has been reduced to five points following the latter's comfortable 5-1 thrashing over Arouca.
Benfica will welcome the return to home soil where they have won all bar one of their 13 matches at the Estadio da Luz across all competitions so far this season - a 1-1 draw with Paris Saint-Germain in the Champions League group stage being the only exception.
However, the Eagles were beaten 1-0 at home against Portimonense last season, courtesy of a second-half strike from Lucas Possignolo, so they cannot underestimate Friday's opponents.
Victories have been hard to come by for Portimonense in recent months, as they have come out on top in only three of their last 13 matches across all competitions.
The Alvinegros Marafados have suffered back-to-back defeats since the World Cup break, with a 3-0 home loss against Gil Vicente in the Taca da Liga followed by a 2-1 league defeat at home to Casa Pia on December 28.
Paulo Sergio's men have slipped down to eighth place in the Primeira Liga standings and they are seven points away from both the relegation zone and the European places.
Portimonense, who are competing in the top-flight for the sixth successive season, have experienced mixed fortunes on the road so far this season, winning and losing three away league games each.
The Alvinegros Marafados picked up maximum points in their most recent away league fixture, beating Gil Vicente 2-1 in November, and they will look to become the first team since Porto in May to beat Benfica on their own patch when they lock horns on Friday.
Benfica Primeira Liga form:
W
W
W
W
W
L
Benfica form (all competitions):
W
W
W
W
D
L
Portimonense Primeira Liga form:
L
L
D
W
L
L
Portimonense form (all competitions):
W
L
L
W
L
L
Team News
Benfica will be without key playmaker Rafa due to suspension after he picked up his fifth yellow card of the season against Braga.
It remains to be seen whether in-demand midfielder Enzo Fernandez will feature in the matchday squad amid interest from Chelsea. The 21-year-old played for 89 minutes against Braga, but he could miss out on Friday if negotiations over a transfer begin to escalate.
Fredrik Aursnes could drop back into centre-midfield alongside Florentino Luis if Fernandez misses out, while Julian Draxler and David Neres are set to start on the flanks, allowing Joao Mario to operate in the number 10 role in the absence of Rafa.
As for Portimonense, midfielder Carlinhos is yet to play this season due to injury and remains sidelined, while attacker Welinton Junior - who has not featured since the end of October - is also on the treatment table.
A back four of Fahd Moufi, Pedro Henrique, Filipe Relvas and Moustapha Seck is set to remain intact, shielding goalkeeper Kosuke Nakamura.
Paulo Estrela, Mohamed Diaby and Gustavo Klismahn are all set to continue in centre-midfield, while Yago Cariello could be supported in attack by Zie Ouattara and Luquinha, the latter of whom scored in the defeat against Casa Pia last time out.
Benfica possible starting lineup:
Vlachodimos; Bah, Silva, Otamendi, Grimaldo; Luis, Aursnes; Neres, Mario, Draxler; Ramos
Portimonense possible starting lineup:
Nakamura; Moufi, Pedrao, Relvas, Seck; Ouattara, Diaby, Klismahn; Ouattara, Cariello, Luquinha
We say: Benfica 2-0 Portimonense
Both teams will be keen to put aside their disappointing results last week and begin 2023 in positive fashion with a victory on Friday.