The game at the Polish capital's National Stadium kicks off at 8:45 p.m. Warsaw time.
The Poles, captained by star striker Robert Lewandowski, are looking to deliver a strong performance against their higher-ranked opponents on home turf.
Poland are ranked 30th worldwide by football's governing body FIFA, while Portugal are No. 8 in the FIFA table.
At a pre-match news conference in Warsaw on Friday, Poland manager Michał Probierz said: "This is a very important match, marking another step toward understanding where we stand. Our recent games against top rivals have exposed some shortcomings that need to be addressed."
He added: "Every match is important, and victories are remembered in history. We want our team to win these kinds of matches regularly, rather than treating each win as a national holiday."
Probierz has previously said that this season's Nations League offers a valuable opportunity to assess players and prepare them for 2026 World Cup qualifiers.
Poland opened its Nations League campaign by defeating Scotland 3-2 in Glasgow last month. The Polish team was then beaten 0-1 by Croatia in its second game in Group 1 of the top League A.
After two rounds of fixtures, Poland are third in their Nations League Group A1, with three points.
Poland will take on Croatia in Warsaw in their next Nations League fixture on Tuesday.
Poland manager Michał Probierz last month released a list of 27 football players called up for the two games.
The squad named by Probierz to face Portugal includes Barcelona striker Robert Lewandowski and other regulars such as Inter Milan midfielder Piotr Zieliński and Southampton defender Jan Bednarek.
The Nations League is the European football governing body UEFA’s newest national-team competition that is now in its fourth edition.
Portugal won the first edition of the Nations League in 2019, while France won the 2020/2021 UEFA Nations League, and Spain triumphed in the 2022/2023 edition.
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Source: IAR, PAP, TVN24, pzpn.pl