Cristiano Ronaldo is due in court in Madrid on July 31 to answer charges brought by prosecutors at Spain’s Hacienda tax authority.
He is accused of using offshore companies to avoid paying at least €14.7 million in tax on ‘image rights’ income.
Experts say jail time is a real possibility if he does not admit guilt and pay a fine.
The four-time Ballon d’Or winner’s camp have maintained that he is innocent.
The boarding of his yacht by customs agents this week is also seen as further provocation.
Reacting at a news conference at UCLA ahead of a preseason training session,
Real Madrid vice-captain Marcelo says he and his teammates will support Cristiano Ronaldo “to the death”.
Marcelo said he would wait to discuss the issue until Ronaldo joined up with the squad.
“I have not spoken with Cristiano about this”, the player said on Friday.
“He knows that his teammates are with him to the death. When he arrives we will speak with him and see how he is.”