Goalkeeper Roy Carroll accepts Northern Ireland's injury crisis at the back is a problem but believes there is still enough experience in the squad to hand Portugal a second bloody nose on Friday.
Manager Michael O'Neill faces the unwelcome prospect of hosting Cristiano Ronaldo et al without three of the four defenders who kept Russia at bay in a shock 1-0 win last month.
Daniel Lafferty is suspended and Craig Cathcart never made it to Belfast due to a knee problem, while Aaron Hughes is rated as a major doubt due to a groin strain.
Lafferty's likely deputy Ryan McGivern also missed training on Wednesday to increase O'Neill's headache, but Carroll can rely on the steadying influence of Gareth McAuley and the returning Jonny Evans in front of him.
"It's pretty bad. We have three players missing from the last game but it is international football, and that is what happens," the veteran shot-stopper said.
"The boys will be in for it and they're still on a high from the last game so we will see what happens.
"It's always difficult changing the back four but it needs experience and I have been around for so long. We have two Premier League players in the middle of defence, Jonny Evans and 'Big G' (McAuley) as well."
Niall McGinn, the Aberdeen forward whose goal gave Northern Ireland a 1-1 draw against Portugal in the reverse fixture in October, was equally optimistic in the face of adversity.
McGinn was not even a regular starter when he put his side ahead in Porto, ruining the occasion of Ronaldo's 100th cap in the process.
Helder Postiga equalised in the last 10 minutes to salvage something for his side, but it was a big moment for the visitors.