"[Fernando Torres] is one of the players [who needs a rest]. You see two or three players who have been playing too many games in the last weeks or months. So it's difficult," Benitez told reporters.
The Blues' manager was unable to confirm the arrival of Newcastle front-man Demba Ba, saying the deal was not yet official but that he hoped to have a new striker by the weekend.
"I think the club is working and hopefully we can see someone else... if we can do the business I hope so [a new striker available for the weekend game]," he said.
Chelsea's loss to QPR at Stamford Bridge marked the end of a four-game winning streak and left them languishing in fourth place, 14 points behind leaders Manchester United but with a game in hand.
"We have to do everything almost perfect if we want to reduce the gap [at the top]," Benitez said.
But he admitted a perfect run was a tall order.
"Especially for us. We were playing so many games with the same players and you could see today that maybe these players couldn't go to the level that we were expecting."
Benitez dismissed criticism that he had fielded a weakened side against QPR by resting midfielders Juan Mata and Eden Hazard.
"We cannot carry on with the same players every game and if you play against a team at the bottom of the table at home you have to trust your players," the Spaniard said.
