Manchester United and Portugal star Cristiano Ronaldo. Photo: AFP.
United said Friday that the 37-year-old forward had been granted additional time off to deal with an unspecified family issue that prevented him from reporting back for practice this week.
The Portugal star has reportedly asked to leave United.
Ronaldo only returned to United last season after 12 years away from Old Trafford but the team finished in sixth place and only qualified for the Europa League rather than the more prestigious Champions League.
The tour will feature games against Liverpool, Melbourne Victory, Crystal Palace and Aston Villa. It will be new manager Erik Ten Hag's first chance to work in depth with the squad.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)