Defender Luis Neto has called on Portugal to produce a professional performance in the friendly away to Luxembourg.
Portugal are riding high in fourth position in the FIFA rankings - some 142 places better off than their lowly opponents.
However, Luxembourg's stock is likely to rise after Aurelien Joachim scored the only goal in stoppage time to stun Greece on Friday.
Zenit centre-back Neto was an unused substitute in the country where he plies his trade on Saturday, looking on as Russia claimed a 1-0 victory thanks to Roman Shirokov's 89th-minute winner.
"It will be a particularly different game, but we are professionals and we take all games seriously for our country, with maximum concentration," Neto said on the Portuguese Football Federation's official website.
"Now we are focused on the match against Luxembourg.
"The coach said he was looking for teams to test new game situations at this point, since there are no low-quality teams.
"All teams are organised. I'm sure that Luxembourg will test us a lot."
Portugal boss Fernando Santos will once again be without Real Madrid superstar Cristiano Ronaldo, with the national team's talisman taking a break for this latest round of friendlies.
In Ronaldo's absence, youngsters Ricardo Pereira, Ruben Neves, Goncalo Guedes and Lucas Joao all made their international debuts in Krasnodar.
"Ronaldo is our reference and leads the team, not only on the pitch," Neto said.
"But there are other players who have a role in the group's leadership and are able to support and help integrate younger players."
Joachim, who plays his club football with Burton Albion in England's League One, identified Greece having "clearly a lack of confidence" on the back of a dreadful Euro 2016 qualification campaign.
The 29-year-old expects Portugal to be a wholly different proposition.
"We made a lot of effort against Greece so we will try to recover well," Joachim told L'essentiel.
"Against Portugal, it will be a completely different game. They will be much more solid defensively and we will not have as many opportunities."