Fernando Santos' side produced a dominant showing in Lisbon on Friday (AEDT) amid the ongoing furore over the absent Ronaldo's scathing interview on Manchester United.

Fernandes' first-half double, the latter from the penalty spot, set Portugal on their way in their final outing ahead of Qatar, before Goncalo Ramos scored after Emmanuel Dennis missed a second-half spot-kick.

Joao Mario added a late fourth and Portugal will now turn their attention to next Thursday's Group H opener against Ghana as they aim to reach the World Cup quarter-finals for the first time in four tournaments.

Fernandes miscued an effort just wide in the opening stages but made amends after nine minutes as he turned home Diogo Dalot's cutback pass.

Joao Felix curled narrowly over before Bright Osayi-Samuel was adjudged to have handled inside the area, with Fernandes sending Francis Uzoho the wrong way with his spot-kick.

A host of half-time changes did little to alter Portugal's dominance, though Samuel Chukwueze forced a rare Rui Patricio save before Uzoho tipped over from Joao Felix.

The VAR deemed Dalot to have shoved Osayi-Samuel inside the area, though Patricio saved Dennis' penalty before Ramos sealed victory by tapping in Raphael Guerreiro's unselfish pass.

A simple Joao Felix offload teed up the final goal as Joao Mario prodded into an empty net.