The Portuguese has not played in pre-season thus far, but could feature against his former club, though he only returned to training last weekend.
Ronaldo's summer has been overshadowed by a trial in Spain, after allegations of tax evasion.
And Ronaldo could return to action against the club where he made his name in Macedonia this week.
Bale, meanwhile, has been heavily linked with a return to the Premier League, as the Spanish giants attempt to sign Kylian Mbappe from Monaco.
The Welshman struggled with injury last season, appearing just 19 times in La Liga, but he scored seven goals.
Bale has subsequently been mooted as a potential target for United, though Jose Mourinho has attempted to distance himself from any bid.