The fixture is one of the biggest mismatches of the round, alongside Sporting Lisbon's clash with Montalegre's fellow fourth-tier opponents Dumiense.
Match preview
Taca holders Porto will hope for a straightforward passage into the last 16, despite a slightly underwhelming start domestically.
Sergio Conceicao led the side to cup glory last season, beating Braga 2-0 in the showpiece occasions back in June.
However, spirits are not as high at the moment, given Porto's unspectacular start to the campaign which sees them down in third.
They are only three points behind Benfica and Sporting, but they have only scored 15 goals in their 11 league games so far, half of the tally Braga have managed so far.
Conceicao's side have been unconvincing on multiple occasions, as relatively comfortable matches on paper have proved more difficult, as they have already drawn with Arouca and lost to Estoril on home soil this season.
Even when Porto have won, their supporters have walked away feeling a little shortchanged, as one-goal wins over Portimonense, Estrela Amadora, Gil Vicente, Farense and Moreirense were all unimpressive.
Porto faced fourth-tier opponents in the previous round in the form of Vilar de Perdizes, and as many of their league games have gone so far, they limped to a slender victory, coming out on top by two goals to nil.
There is no doubting Porto have kept their finest performances for Europe so far, winning 3-1 at Shakhtar Donetsk and 4-1 at Antwerp, as a draw on matchday six against the Ukrainians will see them through to the knockout rounds.
Visitors Montalegre have much different thoughts on their agenda, as they are currently focusing on an instant return to the third tier, and an improbable victory here that would see them reach the last 16 for just the second time.
On that occasion, Montalegre faced formidable opposition in Benfica, but held them to a very impressive 1-0 defeat, as they exited the campaign with their pride still intact.
This will be their fourth match in the competition already, having already beaten Mondinense, Peniche (on penalties after playing 50 minutes with 10 men) and Pevidem.
Facing Porto will be a much different challenge, as the holders are the first side above the fourth tier that Montalegre will face in the competition this season.
New manager Tony has them playing well in Group A of the Campeonato de Portugal though, as they currently sit third and stand a good chance of bouncing back after last years relegation from Liga 3.
Porto Taca de Portugal form:
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Porto form (all competitions):
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Montalegre Taca de Portugal form:
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Team News
Many changes are expected for Porto as Conceicao will most likely have more than one eye on their trip to Barcelona next week.
The manager made seven changes to the side in the last round, including promoting B-team striker Danny Namaso.
Namaso could come in again given some of the injury concerns in attack for Porto, with Gabriel Veron and Ivan Jaime in behind both out.
Defenders Wendell and Ivan Marcano are also absent, along with goalkeeper Samuel Portugal, who is recovering from a groin injury.
The visitors could well stick with the same side that won in the previous round, but winger Angola came off the bench to score a late winner, so will hope for a start ahead of Andre Dias.
Braga loanee Edu is likely to remain on the bench as starting striker Alex netted another two goals in their win over Limianos in their last outing, as also led the line in the win over Pevidem in the last round.
Porto possible starting lineup:
Claudio Ramos; Joao Mario, Jose Pedro, Fabio Cardoso, Andre Franco; Pepe, Nico, Grujic, Galeno; Namaso, Fran Navarro
Montalegre possible starting lineup:
Bruno Pio; Edu Machado, David Santos, Douglao, Flavio Goncalves; Ruben Neves, David Moura, Mane; Andre Dias, Alex, Boakye
We say: Porto 3-0 Montalegre
Even with many personnel changes, there is not much doubt that Porto will progress with ease, but a narrow scoreline could see Conceicao come in for more criticism.