Benitez accused Materazzi of being "a liar" as he responded to the criticism handed down by the Italy international when he was asked to comment on Benitez's brief stint in charge of Inter in 2010.
Now Materazzi has stepped up his attack on Benitez with insults broadcast on an Italian website Gazza offside.
"So I'm a liar," he questioned. "He's thin then, so that gives reason to call me a liar.
"It pains me to say good luck to Chelsea but I will anyway. I feel sorry for their fans. If I was president of a club, I would not trust him with my team."