Head coach Roberto Martinez has kept faith in his ageing captain, and the Al-Nassr striker is expected to resist suggestions he should be rested, again holding off Goncalo Ramos to lead a star-studded attack.
The composition of his back-up cast is less simple to predict, as Sporting duo Pedro Goncalves and Francisco Trincao were both recalled this month, and they will again compete with Diogo Jota, Joao Felix, Rafael Leao and Pedro Neto for selection in the final third.
Paris Saint-Germain pair Joao Neves and Vitinha could link up in midfield, as Martinez has mentioned their potential as a partnership, but Joao Palhinha - now of Bayern Munich - is also in contention to start.
Portugal switched from a back four to a three halfway through Thursday's game against Croatia, so it remains to be seen which setup will be used versus Scotland.
The versatility of Diogo Dalot - who scored at both ends in midweek - gives the hosts several options, as he can fill in on either flank or as part of a three-man defence.
With such an abundance of talent available, Martinez could even afford to omit Joao Cancelo and Francisco Conceicao from his squad this time around, and he may still decide to rotate his resources.
Newcomers Geovany Quenda, Renato Veiga and Tiago Santos are unlikely to start, but all three will hope to make their senior international debut from the bench.
Portugal possible starting lineup: Costa; Dalot, Dias, A. Silva, Mendes; Palhinha, Vitinha; B. Silva, Fernandes, Leao; Ronaldo