The 53-year-old has voiced his admiration for the prolific forward, and feels Jose Mourinho has done a good job this season
The Portugal international has already netted 19 goals in 16 official appearances for Madrid in 2013, including crucial goals against Manchester United and Barcelona, and Schuster has nothing but praise for the prolific attacker.
"He has proven that he is willing and capable of carrying the team on his shoulders, which is a good thing. I'm not in the least bit surprised," Schuster told Marca.
"Cristiano Ronaldo's hunger, which he shows in every match, and his desire to score goals and win stand out most for me."
Schuster, who wore the Madrid jersey from 1988 until 1990, then went on to stress that Jose Mourinho has done a good job to prepare the team for the most important stage of the season.
"I think he wasn't doing anything terrible before and hasn't started doing anything special now. He has a consistent way of working and he has the team primed for the business end of the season, the last three months during which the Champions League is at stake.
"Real Madrid have risen to the occasion and should be recognised for that. I think they can keep up the level they showed in the Clasicos and at Old Trafford. They were worthy winners and proved that when push comes to shove, they are up to the task."
Madrid are currently preparing for the Liga match at home against Real Mallorca.