After a goalless and uninspiring first-half, Chelsea piled on the pressure and had a goal disallowed when Frank Lampard’s effort was ruled out for offside.
But QPR snatched a shock win when Shaun Wright-Phillips drilled home from the edge of the box after the Blues failed to properly clear a corner in the 78th minute.
“A lot of things went wrong today,” said the Blues interim boss, whose side remain in fourth and a point behind third-placed Tottenhan.
“We knew we were playing against the bottom of the table side and we spoke about that.
“We knew we had to be focused but we did not have the tempo and some players may have been tired. It was going wrong against a side who played deep and were organised.
“The main thing for me is to analyse why we were making the mistakes, then reinforce the players and keep pushing.”
Chelsea are set to begin talks with Demba Ba after Newcastle accepted a bid from the Blues on Wednesday.
And Benítez admits he is looking forward to having the option of resting Fernando Torres, with Ba’s arrival set to be confirmed this week following Daniel Sturridge’s departure to Liverpool.
He continued: “I have not spoken with our people so don’t know the situation regarding Demba Ba. Fernando Torres has been playing every game and you could see he was tired.”
Benítez also confirmed that goalkeeper Petr Cech is set to be out of action for “two or three weeks” after picking up an adductor problem at the weekend.
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