The Brazilian international had been out of action for almost one month with a hamstring injury, but returned to the team at the Bernabeu.
"I was eager to return," he told reporters.
"I wanted to help the side and, thanks to God, the physios and doctors that have helped me and ensured I'm 100%.
"When I'm available to help the side and the boss doesn't pick me it's normal I'm not happy and I want to play. The manager decides and I was to play as many games as I possibly can."
It is currently unclear whether Marcelo will start the second leg of their Champions League semi-final against Bayern Munich next week.