The Israeli, who left the Merseyside club to join Premier League champions Chelsea earlier this month, said Benitez deliberately destroyed his confidence and showed him a lack of respect.
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"Everyone asks me why I left Liverpool," Benayoun is quoted as saying in the News of the World. "There is only one reason - Rafa Benitez.
"He never treated me with the respect I deserved. If I played well, I never felt he gave me credit.
"When I scored, I still expected to be out of the team the next game. And when the fans wanted me to play, Benitez told me he couldn't understand why...
"He tried to destroy my confidence. You can't treat a player like this and expect him to be happy. I felt so unhappy but, out of respect to the club, I never spoke out. The players and the people at the top of the club knew how I felt."
Benitez, who was appointed manager of Inter Milan a week after leaving Liverpool, was sacked as Reds boss in June after after overseeing a dismal campaign.
They were eliminated from the Champions League in the group stages before failing to qualify for next season's competition after finishing seventh in the Premier League.
The Spaniard's final year in charge was also marked by the high-profile departure of Spain midfielder Xabi Alonso to Real Madrid and a public falling out with winger Albert Riera.
"I don't want to speak on behalf of other players at Liverpool, but people know what happened to Albert Riera and Xabi Alonso," Benayoun added.
"It was the same for me. Benitez tried to break me like he broke Riera."
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