Steve Coppell's men looked set to make it three wins on the bounce as they took an early lead at Anfield through a debatable free-kick given away by Alvaro Arbeloa.
John Oster drove the ball low across the edge of the box by to an unmarked Marek Matejovsky whose right-footed thunderbolt flew into the top corner above a stunned Jose Reina in the Reds goal.
The home side started to settle and could have squared the game four minutes later when Torres showed blistering pace down the left before putting in a deep cross to Xabi Alonso on the edge of the area, but his looping shot only managed to clip the top of the bar.
The Reds piled on the pressure and deservedly equalised on 19 minutes after some patient build-up play in deep in Reading's half.
Liverpool's latest £18million signing Javier Mascherano latched on to the ball and skipped past Steven Hunt before unleashing a rare right-footed rocket from 25 yards.
Rafa Benitez's men thought they had taken the lead on the half-hour when Steven Gerrard's cross was bravely met by Ryan Babel whose header beat keeper Marcus Hahnemann, only for the flag to be instantly raised for offside.
The home side finished the first half the stronger of the two sides and Alonso's volley had everyone beaten but the post.
Liverpool started the second half as if the break had never happened, instantly attacking the Reading back line and taking the lead three minutes in through Torres' header.
A high floated free-kick from Gerrard allowed the Spanish hit-man to rise unchallenged in the six-yard box as he nodded home his 20th and probably easiest goal of the season.
The game should have been finished off just after the hour mark when Babel seemed to have done all the hard work to create a shooting chance for himself in the box but his wild swing could only find the top tier of the stand.
The visiting fans reacted to manager Steve Coppell's decision to replace Shane Long on 63 minutes with a chorus of boos and the furious winger ripped off his shirt and threw it at his coach.
Reading frantically searched for an equaliser in what turned out to be a scrappy second half but the Reds defence held strong with vital blocks and challenges from both Jamie Carragher and the impressive Martin Skrtel.
The visitors could have pinched a point right at the death when substitute striker Dave Kitson found himself a few yards out but his angled shot was blocked by Gerrard who flung his body in the path of the goal-bound effort.
The replay clearly showed the ball hitting the Liverpool captain's arm but the referee and his assistant waved away the desperate Reading pleas.