The Real Madrid star trained with the national team on Sunday as they prepare for the World Cup in Brazil, easing concerns over his fitness ahead of their opening game against Germany on June 16.
Portugal have struggled without Ronaldo recently, having been held to a 0-0 draw by Greece before needing a late goal to beat Mexico 1-0, and Vieirinha was delighted to see the team's talisman back on the field as they prepare for Tuesday's friendly against the Republic of Ireland.
"For us it is important to know how important Cristiano Ronaldo is," he told reporters.
"His presence on the national team gives motivation to the other players. It is very important to us and very important to Portugal, because he is another player who will help the team.
"I think the last training answered the questions that everyone had. I think this training shows he came to help the team and all of us are happy with it.
"We hope this stays in this way, without creating a lot of expectations with him being back in the team.
"I believe that was the best thing that could have happened in recent days."