Shaun Wright-Phillips scored a 78th-minute winner against his former club as Rangers secured their first triumph at Stamford Bridge in three decades.
Chelsea are now 14 points points behind leaders Manchester United, albeit with a game in hand, but Benitez insists his side will stay focused hauling in their rivals.
"I didn't like to talk about (the title) before and I don't like to talk about it now," ths Spaniard said.
"Obviously you can't make mistakes when you have this gap. We have to approach one game at a time and see what happens. Every game is important."
Benitez started with Ramires, Juan Mata and Eden Hazard on the bench but insisted his rotation policy was justified given the club's heavy workload.
"We were tired and weren't precise. We made a mistake and gave them their chance," he added.
"I don't regret the changes because we can't carry on with the same players in every game.
"If you're playing a team at the bottom of the table at home, you have to trust your players and I trust them."