With 10 league games to go, the visitors trail second place by six points and league leaders Sporting Lisbon by seven points, while their hosts only lead the relegation zone by a single point.
Match preview
Portimonense return to the Estadio Municipal de Portimao on Friday with the aim of improving their standing in the fight for Primeira Liga survival this term, having climbed out of the bottom three last time out despite being in the midst of a tough run of form.
From their 24 league games so far this term, the Alvinegros have managed just 23 points, suffering 13 defeats in that time while only managing six victories.
Two of those wins came in a three-match span in January over Farense and Boavista in January to give their survival hopes a huge boost, but they have been unable to build a sustained improved run since, earning just two more points from the last five attempts as they firstly suffered defeats at the hands of Arouca and fellow strugglers Estrela Amadora.
Then on the back of a creditable 1-1 draw with Vitoria de Guimaraes and a 4-0 thrashing away at Benfica, Paulo Sergio's side most recently hosted basement side Vizela on Sunday and came away with a share of the spoils from a goalless draw, having played the final 20 minutes with 10 men after Pedro Henrique was sent off.
While that result did see Portimonense climb out of the drop zone, they may be left somewhat disappointed by a goalless stalemate at home to the division's bottom side while only gaining a one-point lead over the bottom three, and they will now be desperate to pull off an upset to correct their form on Friday ahead of the final run-in in a competitive relegation dogfight.
They face an unenviable task, though, as Porto arrive in fine fettle having won four of their last five games across all competitions.
After falling two points short of Benfica in the Primeira Liga title race last time around, Porto have certainly had a disappointing league campaign on the whole this term, currently sitting third and trailing leaders Sporting Lisbon by seven points having played a game more.
Indeed, Sergio Conceicao's have already dropped points on eight occasions, more than in each of the previous two seasons, including a 1-1 draw away at Gil Vicente in late February after an impressive 1-0 home victory over Arsenal in the first leg of their Champions League round-of-16 tie thanks to Galeno's late goal.
Os Dragoes would bounce back from that disappointing draw with a 2-1 win away at Santa Clara on Thursday to book a Taca de Portugal semi-final place, before most recently hosting rivals Benfica in O Classico on Sunday and dishing out a historic 5-0 beating, as Galeno netted another two goals in the first half before Wendell, Pepe and Danny Namaso added their names to the scoresheet.
Such a triumph saw Porto narrow the gap to Benfica to six points with 10 games to go in the fight for the second Champions League spot, and with their title hopes all but gone, Conceicao's men will now bid to build momentum and apply further pressure to their rivals with another win on Friday before travelling to London for the second leg against Arsenal next week.
Portimonense Primeira Liga form:
W
L
L
D
L
D
Porto Primeira Liga form:
W
D
L
W
D
W
Porto form (all competitions):
L
W
W
D
W
W
Team News
Portimonense should field a similar starting XI from their draw against Vizela last time out, albeit with one enforced change in defence, as Pedro Henrique will serve a suspension after being sent off in that game.
In his absence, Goncalo Costa should step into the back four with Filipe Relvas shifting along to join Alemao in the centre, while Nonoca and Dener will continue to play key roles at the base of the midfield.
Further forward, Carlinhos will continue to play a key role behind a lone striker, having notched up eight goals so far this season, while Sylvester Jasper and Helio Varela are danger men on the wings.
Following a rampant display in O Classico last time out, Porto could be unchanged on Friday with Ivan Marcano and Zaidu Sanusi remaining sidelined by injury, although full-back Wendell will be subject to a late fitness test.
Pepe and Otavio will continue at the heart of a back four, with Nico Gonzalez and Alan Varela bound to again partner up at the base of the midfield, despite competition from Stephen Eustaquio.
In their 4-2-3-1 shape, the line will again be led by Evanilson with support from the dangerous trio of Francisco Conceicao, Pepe and in-form Galeno, who has netted five goals in the last five games to take his tally to 12 for the season alongside 10 assists in all competitions.
Portimonense possible starting lineup:
Nakamura; Formiga, Alemao, Relvas, Costa; Nonoca, Dener; Jasper, Carlinhos, Varela; Carrillo
Porto possible starting lineup:
Costa; Mario, Pepe, Otavio, Wendell; Gonzalez, Varela; Conceicao, Pepe, Galeno; Evanilson