Gerrard still remains the bigger doubt after minor groin surgery but the Anfield club's medical staff are reportedly encouraged by Torres' progress in recovering from a hamstring injury.
The presence of either player would be a huge boost to Benitez, who has yet to beat Liverpool's arch-rivals in the league since arriving in 2004.
"It is always more difficult to prepare for the match with injuries because you know that if they are fit we will use them, but in this case you never know," Benitez said.
"It is better to avoid saying whether they can be available - it is difficult to say if they can play or not because they may have not played for 10 or 15 days.
"But they are both working hard with the physios and are improving, so there's still some time to decide."
Last weekend Gerrard said the United match would come too soon for him, and he was targeting the Champions League match against Marseille next Tuesday.
However, his manager is more optimistic, although he has confidence in the rest of the squad should his captain not make it.
"You never know, he is still progressing. The key is the fitness of the player - it makes a massive difference if he has confidence. That is the main thing for him," the Spaniard told the club's website liverpoolfc.tv.
"Clearly we have enough quality in the squad, so it is always important to look to the other players and sometimes they can give more to you than the big names.
"They can have the same quality and passion and they also have a lot to prove to the supporters."