As Sky reported, Ronaldo was undergoing medical examinations for the weekend in Lisbon.
The management of United announced on Friday that they have reached an agreement with Juventus on the transfer of 36-year-old Ronaldo.
Ronaldo agreed on the personal terms of the two-year contract.
According to Sky, Manchester United will pay around 15 million euros, with bonuses of eight million euros for the captain of the Portuguese national team.
Ronaldo thus returns to Old Trafford, where he played 292 games from 2003 to 2009 and scored 118 goals. He has won three Premier League titles, the Champions League, the FA Cup, two League Cups, the Community Shield and the World Club Championship.