Some 80,000 fans are expected to be in attendance while millions more will watch the live broadcast around the world.
"No one knows what will happen in the four weeks of the tournament, but everyone is sure that it will be memorable," Ronaldo said.
"Of course it is also an emotional one for the hosts. After so much hard work, suddenly the whole world is gathered in your backyard to celebrate their love for football. I felt that in Brazil four years ago and I am now happy to share this excitement with the Russians as well."
No details were given about the role Ronaldo will play in the ceremony, whose creative director is local producer Felix Mikhailov.
"We'd like to invite football and music fans to party with us in Russia, in the stadium, or to tune in their TVs a little earlier for an unforgettable show," Williams said.
Meanwhile, another Brazilian legend Pele may not be part of the opening ceremony and the inaugural match of the FIFA World Cup on June 14, having cancelled his scheduled trip to Russia because of ill health. Pele's spokesperson didn't confirm his absence but said that he had some problems with his legs and a clearer picture about his presence would emerge on Tuesday. "He is feeling ill. He has problems in his legs," his spokesperson said.
Edson Arantes do Nascimento, the football legend -- who won the Jules Rimet Cup, used as the World Cup trophy from 1930-1970, three times -- is one of the main guests invited at the opening ceremony in Luzhniki Stadium.
(With IANS Inputs)