Federer, who lifted the trophy in his last two appearances in 2005 and 2012, last suffered defeat in the event against Tim Henman in 2004.
“I’m very disappointed, I have some regrets about this match,” said Federer, who came back from two sets to love down to beat Benneteau in the third round of Wimbledon last year.
“He played great and created more chances than I did. He deserved to win. It was a tough loss, but they do happen. Being broken so many times (five) indoors won’t get the job done. My game was up and down overall.
World No 39 Benneteau will play a Saturday night semi-final against compatriot Gilles Simon. “This was a dream match, and I played like a dream,” said Benneteau after his second career win over the World No 2 Swiss ace.
Del Potro in Rotterdam final
Meanwhile, Juan Martin del Potro beat Bulgarian youngster Grigor Dimitrov 6-4, 6-4 on Saturday to move into his second straight final here. “I’m surprised not to see Federer in the final, but Benneteau plays well on hardcourt and Roger can have a bad day like anyone.” said Del Potro.