A defeat on the final day, coupled with a win for Rio Ave and a result for Boavista, would see Paulo Sergio's side fall into the relegation playoff place, resulting in them going into another battle to avoid dropping to the second tier.
The hosts come into this game having failed to confirm their safety due to three consecutive defeats in the Portuguese top flight.
They suffered a harmful 1-0 loss at home to fellow strugglers Boavista last time out, as defender Jackson Porozo netted the only goal of the game in the final 15 minutes to snatch all three points for the visitors.
That saw Boavista move just one point behind Portimonense, while Paulo Sergio's side sit three points above Rio Ave in the relegation playoff place and Farense in the automatic drop zone going into the final day of the season.
Due to the Primeira Liga's priority on head-to-head results, the Algarve side are safe from the automatic drop thanks to their win over Farense earlier in the season, but two losses to Boavista and a draw and a defeat to Rio Ave this season means that they will finish in the relegation playoff place if they are to lose and Boavista avoid defeat and Rio Ave win.
With a three-point lead over Rio Ave, the task is simple for Sergio's men, as they simply need to avoid defeat on Wednesday to move out of reach of the 15th-placed side.
That is by no means a straightforward task though, as they welcome a Braga side who have finished comfortably in fourth spot thanks to an impressive league campaign.
Braga returned to winning ways last time out, as they defeated 10th-placed Moreirense 2-1 at home on Friday.
Abel Ruiz put Os Arcebispos ahead on the stroke of half time, but Rafael Martins netted an equaliser in the 87th minute and the game looked set to finish level until Braga were awarded a penalty in the 95th minute, which Joao Novais made no mistake in converting to seal the three points for Carlos Carvalhal's side.
That followed their most inconsistent run of the season, having gone four league games without a victory leading up to that match.
As a result, Carvalhal's men have fallen well behind the top three in the table, eventually finishing in fourth spot with a 13-point lead of their own over fifth-placed Pacos de Ferreira.
While they will be disappointed not to have achieved a top-three finish, Os Arcebispos have bettered last season's points tally of 60 by three points so far, with the chance to take that to a six-point improvement with a victory on the final day, as they look to build momentum going into the Taca de Portugal final against Benfica on Sunday.
Portimonense's only absentee on Wednesday should be midfielder Lucas Fernandes, who will continue his spell on the sidelines through injury.
Their line will be led by Beto, who has netted an impressive tally of 11 goals in 29 league appearances alongside three assists.
He should be supported by Aylton Boa Morte, who has complimented the young forward well with five goals and four assists in Primeira Liga action this season.
Midfielder Andre Castro was fit to start last time out after he picked up a worrying knock in the previous game, but he may not be risked with another match in quick succession.
With nothing particularly to play for in the league, combined with the cup final on Sunday, Carvalhal may choose to rotate some of his key players to ensure they are fresh and healthy for Sunday's crucial encounter.
Portimonense possible starting lineup:
Samuel; Possignolo, Willyan, Antonio; Moufi, Clemente, Fabricio, Sa, Anzai; Boa Morte, Beto
Braga possible starting lineup:
Matheus; Esgaio, Tormena, Silva, Sequeira; Novais, Musrati, Horta, Galeno; Piazon, Sporar
We say: Portimonense 1-2 Braga
While Portimonense will battle hard for a result to confirm their survival without having to worry about other results, Braga should have enough to finish the campaign with a victory on Wednesday.
After a disappointing run, the late winner last time out should lift the mood in the Archbishops' camp going into the final day, and they will be desperate to pick up another win as they go into a crucial cup final at the weekend.