The Portuguese international's future with the Red Devils has been the subject of intense speculation since Real Madrid's president, Ramón Calderón, expressed his wish to bring in the Premier League hot-shot.
Although the 23-year-old has spoken of his will to stay at Manchester United on multiple occasions, he unveiled upon his arrival in Lisbon that his future may in fact only be decided in a couple of weeks.
"I do not have anything with Real Madrid," Ronaldo said. "I have a contract with Manchester United and it is with my club that I will speak to. There can be further news in the next two weeks."
Ronaldo, meanwhile, stated that he is committed to "repeating or improving" this season's performances next campaign.
On Portugal's chances at Euro 2008, Ronaldo added: "It would be fantastic to be European champion for Portugal. It is a hard dream, but we are thinking game by game.
"The first game in the group stage will be crucial. We have conditions to create a great squad."
Ronaldo and Manchester United team-mate, Nani, will now travel to Viseu, where the Portuguese national squad are currently training.
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