Ronaldo, who has asked to leave Old Trafford, was due to begin training with the rest of United's international players at Carrington on Monday but was given permission by the club to take an extended break because of "family reasons."
- Ogden: Ronaldo leaves Man Utd high and dry
The squad are due to fly to Bangkok at 4.30 p.m. BST (11.30 a.m ET) on Friday but sources have told ESPN that manager Erik ten Hag does not yet know whether Ronaldo plans to train in Manchester this week or make himself available for the tour.
United's first friendly is against Liverpool in Bangkok on July 12.
United insist the 37-year-old, who scored 24 goals last season, is not available for transfer and that Ten Hag "wants and expects" him to be part of the squad next season.
However, sources have told ESPN that in reality that stance is softer, although they would prefer Ronaldo moved abroad rather than join Premier League rivals Chelsea. He has a year left on his contract at Old Trafford with the option of another year.
Malacia completed the formalities of his move from Feyenoord at Carrington on Monday, while Eriksen has verbally accepted the offer of a three-year deal.
Sources have also told ESPN that United have not given up hope of signing Lisandro Martinez in time for the defender to be part of the summer tour.
The club are vying with Arsenal for the Ajax player, who has told the Dutch club he wants to move to the Premier League this summer.