Portugal coach Fernando Santos insisted on Tuesday that Cristiano Ronaldo's morale has been unaffected by recent disappointments with Juventus.
European champions Portugal play their opening 2022 World Cup qualifier against Azerbaijan at the Juventus Stadium in Turin on Wednesday, due to coronavirus travel restrictions.
Ronaldo has been under fire in Italy after Juve's Champions League last-16 exit to Porto and the weekend defeat by Benevento which left them 10 points behind Serie A leaders Inter Milan.
Describing the 36-year-old Ronaldo as a "very good friend", Santos said he found the player to be in high spirits.
"We've always been close to each other, very good friends, we don't really have a coach-player relationship," the 66-year-old Santos told a press conference.
"(Ronaldo) certainly represents great quality, he always shows great happiness and joy when he's with the team."
Ronaldo is bidding to break Ali Daei's all-time men's international goalscoring record, with the former Real Madrid attacker only seven goals short of the Iranian's mark of 109.
"He's an important player, probably the best in the world," added Santos. "I don't think he has any problem in terms of mentality at the moment."
Portugal have qualified for the World Cup finals seven times, reaching the semi-finals in 1966 and 2006.
Alongside Ronaldo, they boast an array of attacking talent, including Manchester United star Bruno Fernandes, Atletico Madrid youngster Joao Felix and Liverpool's Diogo Jota.
And after winning their first major title at Euro 2016, Santos believes the World Cup "is not really a dream, but something that can definitely come true".
"We know Ronaldo always wants to conquer new trophies, but all the players want to win the World Cup," he said.
"We can fight to become the world champions."
Despite fifth-ranked Portugal being favourites against Azerbaijan, ranked 108th, Santos warned: "We mustn't underestimate anyone. We know Azerbaijan can be quite dangerous on the counter-attack."
Although defender Pepe is out after suffering an injury while playing for club side Porto, Ruben Dias believes the veteran's absence "will change nothing".
"We have a very clear playing idea. We can't depend on just one single player. We have to adapt, there will be other players," said the Manchester City defender.
"We want Portugal to be recognised as a truly important team.
"What we're doing here is fighting for the World Cup.
"We have great ambitions, we want to win. Cristiano is obviously fundamental for the national team.
"We're trying to integrate the new players with Cristiano to create a new team."
The European champions also travel to Serbia on Saturday and Luxembourg three days later.