The hosts have fallen worryingly close to the bottom three of the Primeira Liga table after a six-game winless run, while their visitors have now lost their last four matches in the top flight.
Match preview
Rio Ave have slipped worryingly close to the relegation zone recently, having failed to win any of their last six league games.
Miguel Cardoso's men suffered a disappointing defeat to strugglers Maritimo last time out, as Diederrick Joel Tagueu netted the only goal of the game after 12 minutes.
That meant Os Rioavistas have now picked up just four points from their last six games in the Portuguese top flight, falling to 14th spot as a result, with just a two-point gap between themselves and Maritimo in the relegation playoff place.
Their struggles this season have mainly come in attack, with only Belenenses scoring fewer than the 22 goals that Rio Ave have netted in 28 league outings.
Cardoso will be desperate for his side to get back to winning ways on Sunday, as they look to put some more crucial distance between themselves and the drop zone.
They take on a Pacos de Ferreira side who sit comfortably in fifth spot, despite a four-game losing run in the Primeira Liga.
Pepa's side come into this game on the back of consecutive defeats to struggling sides, as they suffered 2-0 losses to Boavista and Farense.
Most recently, goals from Ryan Gauld and Fabricio Isidoro fired 17th-placed Farense to a surprise win at the Estadio da Mata Real, after Boavista also boosted their survival bid with a fairly comfortable 2-0 win over Os Castores.
As a result, Pepa's men have fallen well behind the top four, with 14 points now separating themselves and fourth-placed Braga.
They will be hopeful of returning to winning ways on Sunday, as they look to improve their chances of achieving European qualification for next season.
Rio Ave Primeira Liga form:
Pacos de Ferreira Primeira Liga form:
Team News
Rio Ave's squad will be majorly boosted by several returns for this game, as Gelson Dala comes back into the side following his red card in the draw with Braga.
Meanwhile, left-back Pedro Amaral and midfielder Felipe Augusto will also return from one-game suspensions, adding to Cardoso's options.
Their only absentee should be forward Andre Pereira, who remains out with a ligament rupture.
Os Castores will remain without midfielder Mohamed Diaby and centre-back Marco Baixinho, as the pair continue spells on the sidelines through injury.
Pacos de Ferreira midfielder Bruno Costa will serve a suspension on Sunday, after he picked up his fifth yellow card of the season last time out.
However, they did welcome important midfielder Stephen Eustaquio back to action in that game, following his suspension for a red card.
Forward Douglas Tanque will look to end his three-game goalless run on Sunday, having netted seven league goals so far this season.
Rio Ave possible starting lineup:
Kieszek; Pinto, Borevkovic, Santos, Amaral; Augusto, Pele, Guga; Mane, Dala, Geraldes
Pacos de Ferreira possible starting lineup:
Jordi; Fonseca, Marcelo, Gonzaga, Uilton; Eustaquio, Ibrahim, Moreira; Singh, Tanque, Ferreira
We say: Rio Ave 2-1 Pacos de Ferreira
Both sides come into this game in poor runs of form, and the tie could definitely go either way.
On this occasion, we see Rio Ave breaking their winless run, as their requirement for a win grows larger and their situation at the bottom of the table worsens, we expect Cardoso to galvanise his side and inspire them to a crucial victory.