Vieirinha believes Portugal have enough depth to challenge at Euro 2016 but must prove their quality against Iceland first.
Portugal must prove why they are favourites against Iceland when the two sides meet in Saint-Etienne on Tuesday, says Vieirinha.
Iceland are taking part in their first international tournament at Euro 2016 and face tricky encounters with Portugal, Austria and Hungary.
Fernando Santos' team are widely anticipated to top Group F, and Vieirinha wants them to immediately move towards matching that expectation.
"We have to be aware that we are the favourites for this game, but we have to prove it on the pitch," said Vieirinha.
"It is essential that we are very concentrated, we cannot let Iceland play how they like. We have to play our game.
"The most important thing is concentration, the attitude and the will that we are going to demonstrate.
"If we want to get to the final, we have to treat our opponents with a lot of respect."
Cristiano Ronaldo is expected to be a key figure for Portugal, but the right-back emphasised there is strength in depth in the squad.
"Ronaldo is Ronaldo – he is always going to be our reference," said Vieirinha. "But there are others with a level that we didn't have in 2014.
"I believe the 23 will give a good account, if the coach takes one and uses another the difference is going to minimal, the quality is here."