Varane has made 25 appearances for the Liga champions this season, and Leboeuf, who won the World Cup and the European Championships with les Bleus, believes his compatriot could eclipse Hierro at Santiago Bernabeu.
“Many compare him to Hierro due to his technique, but on the physical level he is stronger and he is much faster,” Leboeuf told reporters.
“He is very comprehensive and if he keeps his head on his shoulders, he has a very bright future. As a defender, he will not be at his top level all of the time.”
The former Chelsea stopper also revealed his admiration for the professionalism that 19-year-old Varane has shown in his short career so far.
“When arriving in Madrid, he was one of the few kids who did not talk money before talking about football. He has the head of an adult. He wants to work and grow. He interests me enormously.”
Varane was part of the France side that were beaten 1-0 by world champions Spain at Stade de France on Tuesday.