Brazil midfielder Lucas, voted fans' player of the year for last season, is in his home country ahead of Copa America.
And he has thanked former Kop boss Benitez for putting so much faith in him.
He said: "He brought me to Liverpool and helped me to develop as a player. When I first came to the club the expectation was really high.
"I'm Brazilian but not everyone is a really skilful player like Romario or Ronaldinho. At the time I wasn't ready to play in the Premier League. My body wasn't ready.
"That's why Rafa is one of the most important people for me. He gave me games and that's the only way you improve.
"It's hard when you are getting criticised but I wouldn't change anything about my career at Liverpool."
Lucas, signed from Gremio for £5m in 2007, added: "I've got no problem with the people who didn't like me before.
"I knew I had to improve to make the fans change their opinion of me.
"There will be more difficult times but I'll handle them."