The visitors, who are on the back of seven straight Primeira Liga defeats, will take the fight to the Municipal de Portimao Stadium knowing that a win could take them out of the relegation zone for the first time in 2021.
Portimonense will be aiming to rekindle their season, after falling to a 2-0 defeat to league leaders Sporting Lisbon last time out.
Following successive defeats to Boavista and Braga, Paulo Sergio's men picked up one draw and one win against Pacos de Ferreira and Gil Vicente respectively, starting a charge from the relegation zone.
However, their surge was halted by Sporting Lisbon, when Zouhair Feddal and Nuno Santos scored first-half goals to hand the Lions a 2-0 win and extend their lead at the top of the Primeira Liga table to 10 points.
While Portimonense have been decent on home ground, sitting eighth in the home form table, their struggles have come on the road, where they have managed just one win and two draws in 11 matches.
They have also struggled for goals so far, and their 18 goals in 20 games rank them as the joint-third worst team in the league for goals scored, alongside Famalicao and Moreirense.
In a crucial contest on Sunday, Sergio's men will host relegation-threatened Maritimo, who have picked up just six points since the turn of the year.
Milton Mendes's men are rock-bottom in the league standings after suffering 13 defeats and two draws in 20 games.
They are currently on a disappointing run and have lost their last seven league matches, most recently a 2-1 home defeat to Porto.
Os Verde-Rubros looked set to grab a surprise draw against Sergio Conceicao's men after Leo's 18th-minute strike cancelled out Mateus Uribe's opener, but a 93rd-minute penalty from Brazilian midfielder Otavio condemned Mendes's men to another defeat.
While the visitors will be aiming to find their feet on Sunday, they face the daunting task of taking on a Portimonense side they have failed to beat in their last five attempts.
In their most recent meeting, the hosts came from behind to grab a 2-1 victory at the Estadio do Maritimo, with Rodrigo Pinho opening the scoring in the second half from the penalty spot, before Dener and Anderson Oliveira scored to complete the comeback for Portimonense.
Portimonense Primeira Liga form: DLLDWL
Maritimo Primeira Liga form: LLLLLL
Maritimo form (all competitions): LLLLLL
Portimonense have a fully fit squad, and Paulo Sergio will look to name his strongest lineup for Sunday's crucial showdown.
On the other hand, Maritimo will be without top scorer Rodrigo Pinho through injury, while Ruben Macedo could be dropped, after facing heavy criticism from the Maritimo fans.
Portimonense possible starting lineup:
Samuel; Moufi, Possignolo, Antonio, Anzai; Sa, Rocha, Clemente; Boa Morte, Beto, Salmani
Maritimo possible starting lineup:
Secco; Winck, Karo, Junior, Africo, Hermes; Macedo, Jean, Bambock; Tagueu, Guitane
We say: Portimonense 1-1 Maritimo
While Portimonense's league position of 13th may be flattering, they have struggled to perform this season, and with just two points separating them and rock-bottom Maritimo, this clash will be a close one.
Both teams are evenly matched on paper, and we predict a share of the spoils with each side scoring one goal apiece.