Estoril are the only side outside of Portugal's top flight still in this competition, having already knocked out two Primeira Liga teams in their journey to the quarter-final.
Wednesday's hosts suffered a heavy 3-0 defeat in Primeira Liga action last time out at the hands of fourth-placed Pacos de Ferreira. However, on the whole, Milton Mendes has brought positive change to the club so far in his tenure.
Since his appointment in December, Maritimo have won five of their nine games in all competitions, drawing two and losing just three matches.
Meanwhile in terms of league form, having taken charge of seven out of Maritimo's 15 league matches, the Brazilian has contributed three of the club's five wins, one of their two draws and only three of eight league losses.
This has seen Os Verde-Rubros steadily climb the Primeira Liga table and move from the foot of the table up to a more comfortable mid-table position in ninth, where they currently sit five points above the automatic relegation spots.
However, their start to the Taca de Portugal campaign was far from comfortable. In the third round, a late Maritimo penalty saw an away tie against second-tier side Penafiel finish 2-2 after 90 minutes, with an extra-time goal making the difference as they progressed through.
This was followed by a home tie against third-tier Salgueiros, where they trailed 1-0 until an 88th-minute equaliser took the tie to extra-time and the game was ultimately won 2-1 courtesy of a goal in the dying minutes of the extra-time period. All five of the goals in these two games were scored by Maritimo's talisman Rodrigo Pinho.
However, a much more convincing performance saw them advance through the round-of-16 as they beat Primeira Liga leaders Sporting Lisbon 2-0, with Pinho on the scoresheet once again before Leo Andrade added a second to book Maritimo a spot in the final eight.
It will be crucial for Mendes that they build on the Sporting result and do not underestimate a side below them in the Portuguese football system.
Estoril will certainly pose a real challenge to their hosts on Wednesday night - they currently sit six points clear at the top of the Segunda Liga, and this could easily have been an eight-point gap too; last time out, Mafra scored deep into added time to hold Estoril to a 1-1 draw, leaving the league leaders to rue their missed chances.
Despite this, they remain heavy favorites to win promotion back to the Primeira Liga after their relegation in 2018.
Having finished third in 2018-19 and sitting fourth when the 2019-20 season was cut short due to COVID-19, the Canarinhos will see this season as their chance to return to the Portuguese top flight at the third attempt.
From their 17 league games, the side have conceded just 10 goals, with no team conceding fewer than this. Meanwhile, their 28 goals is only matched by one other club, seeing them pick up an outstanding tally of 38 points at this stage.
Estoril have been equally impressive in the Taca de Portugal too, coasting past lower-league opposition in Sertanense and Lusitano in the second and third rounds, winning 4-0 and 5-0 respectively.
The next two rounds presented tough obstacles in Primeira Liga opposition but Estoril impressively progressed through both rounds to reach the final eight.
Firstly, they hosted struggling top-flight side Boavista, when goals from Miguel Crespo and Hugo Gomes gave the Segunda Liga side a 2-0 lead and 90th-minute Boavista strike was just a small blemish on an impressive victory.
They then faced a somewhat tougher test as they travelled to mid-table Rio Ave, but once again Estoril started bright with first-half goals from Abdul-Aziz Yakubu and Andre Vidigal giving their side a 2-0 lead at the interval. Despite a goal from Gelson Dala just past the hour mark for the hosts, Estoril held on to see out another 2-1 win.
Furthermore, the Estorilistas have lost just one of their last 20 matches in all competitions this season, falling to a 3-1 loss against a strong Braga side in the Taca da Liga quarter-final. This should send a strong message to Wednesday's opponents, who cannot afford to underestimate Estoril, a team in some excellent form.
Maritimo Taca de Portugal form: WWW
Maritimo form (all competitions): WDLWWL
Estoril Praia Taca de Portugal form: WWWW
Estoril Praia form (all competitions): WWWWDD
Maritimo are faced with a huge issue coming into this important cup tie as top scorer Rodrigo Pinho has been out after a positive COVID-19 test.
The German-born forward has scored 15 goals from 13 appearances in all competitions this season and has provided six of the side's seven goals so far in the Taca de Portugal.
Abdul-Aziz Yakubu has 10 goals in league and cup action so far this season from 18 appearances and will lead the line for Wednesday's visitors.
The away side should have a full squad to pick from and will be expected to field their strongest possible side in this huge game for them as they look to progress to the semi-final.
The defensive pairing of Hugo Gomes and Hugo Basto has been formidable this season, conceding just 10 goals in 17 league games, and they come up against a weakened Maritimo attack.
Maritimo possible starting lineup:
Abedzadeh; Andrade, Africo, Junior; Winck, Bambock, Guitane, Pelagio, Hermes; Joel, Milson
Estoril Praia possible starting lineup:
Figueira; Soria, Gomes, Basto, Joaozinho; Gamboa, Crespo, Rosier; Harramiz, Vidigal, Yakubu
We say: Maritimo 0-2 Estoril Praia
We believe Estoril will get a third consecutive victory over top-flight opposition in this clash. The absence of Rodrigo Pinho has hit Maritimo very hard and they have struggled to find goals from other sources.
We don't see them breaking down a strong Estoril defence, while Abdul-Aziz Yakubu could look to add to his goal tally and fire his side into the semi-finals.