Portugal boss Fernando Santos does not know what else can be said about Cristiano Ronaldo after his starring role in his side's Nations League win over Switzerland.

The veteran forward bounced back from being benched for Friday's (AEST) opener against Spain with a brace as he led the host side to a 4-0 rout in Lisbon.

The result maintained an unbeaten start to the latest iteration of the competition for Portugal - and further underlined the vital role its captain plays in its success.

Speaking afterwards, Santos - who together with Ronaldo delivered UEFA EURO 2016 glory six years ago - admitted he has no further words to describe one of the game's greatest figures.

"I don't know what else to say," Santos said. "I will repeat that he is the best player in the world.

"What more can I say? I think it's all been said."

"I'm a coach who's happy when I win and when the team plays like they've practiced," Santos added to SportTV of Portugal's overall performance.

"After the first few minutes, we got the ball back and controlled the game. We could have done one or two more in the first half.

"In the second half the pace dropped, [but] the players are not machines. We scored another goal.

"Switzerland created some problems, but we always found the right solutions. It's more to Portugal's credit."