Lee has praised the mental strength of the Brazilian midfielder as he shrugged off criticism last season to make his 100th Liverpool appearance in the 2-0 win over Spurs on Wednesday.
"It's a great achievement to play 100 games for this football club," said the assistant manager.
"He has shown a great strength of character because he has had a lot of criticism and he is doing a great job for this football club.
"To play 100 games for this club is immense. He has come on a lot this season. There is room for improvement as is the case for each and everyone of us at this club.
"He wants to improve, he wants to listen and he wants to learn. So when you have characters like that you have got a chance to do well.
"He has had his difficult times because he's not everyone's favourite player but we know at this club just how good a job he does for us.
"Working with him on a daily basis he is a great character and he has shown a great strength of character."