Torres put in one of his worst performances of his Chelsea career two days ago. The £50million striker touched the ball just 19 times during his 81 minutes on the pitch and could only muster two feeble attempts on goal.
The Blues fans have stood by their most expensive import despite his patchy form throughout his two-year spell at Stamford Bridge, but on Wednesday they gave the 28-year-old both barrels, sarcastically applauding the player as he left the field having called for Demba Ba's introduction since half-time.
Benitez revealed that part of the reason why Torres did not play well was because the Spaniard had been struggling with illness, and his only other replacement Ba was not fully fit as he had a hamstring injury.
"I could not explain it before the match, because (Swansea manager) Michael Laudrup would have known, but Fernando had a stomach bug and Demba Ba had a niggle," Benitez told a press conference.
"The club doctor was giving Fernando tablets, but I told him he had to play because we couldn't play Demba Ba. So Fernando was playing with the problem. I was really pleased with him because he was trying to play despite the problems he had."
Part of the reason why Benitez was appointed Chelsea's interim manager was due to his good relationship with Torres. It was anticipated that the former Valencia boss, who managed Torres at Liverpool for three and a half years, would bring the best out of the former Atletico Madrid man.
Torres' barracking on Wednesday may prove to be a big blow to relations between the Blues fans and their star striker, but when asked whether he thought Torres could win them around, Benitez said: "Yes, the main thing a player can do is to concentrate on your job and Fernando is really, really trying.
"If he scores goals again it will be easier. Fernando concentrated on trying to do his job (despite his illness) and that is the sign of a great character.
"He is trying to give his best. In training every day he is giving 100 per cent every session. Because the club paid big money everybody is expecting a relation between money and goals to be easy."