Torres had the first real opportunity when he flicked a ninth-minute Gerrard corner inches wide of the far post under pressure from Ryan Nelsen.
Steven Reid then almost gifted the Reds an opener after he played a suicidal backpass to Friedel that was intercepted by Torres, but the American goalkeeper managed to block.
The subsequent throw-in was sent to the impressive Dirk Kuyt, who held the ball up for Gerrard, but he disappointed with the finish.
Then came two moments of controversy.
First, after 17 minutes, Gerrard burst onto a through ball played into the left-hand side of the Blackburn area. Friedel rushed out to intercept and contact was made, although it was debatable as to whether it was instigated by Friedel or Gerrard.
Referee Alan Wiley waved Gerrard’s penalty claims away, and he responded in a similar manner when, eight minutes later, Gerrard was pushed over on the edge of the box by Christopher Samba.
He was racing through on goal when the Congo defender barged him off the ball and Gerrard was incredulous that the decision did not go in his favour.
Blackburn also had a dubious decision go against them, when Jason Roberts saw a goal disallowed after the offside flag was hastily raised for an infringement by Santa Cruz, who was not interfering with play.
Otherwise, Liverpool somehow failed to make their dominance count. Gerrard mishit another clear-cut chance laid on by Kuyt, who himself missed a great opportunity when he headed a Gerrard corner wide after being found unmarked at the far post.
And they took a deserved lead after a moment of brilliance from Gerrard.
Santa Cruz gave the ball away to substitute Yossi Benayoun, and the Israeli looked to his right for Gerrard, who still had it all to do. With England boss Fabio Capello watching in the stands, the Liverpool skipper cut inside, played a clever one-two with Lucas and nutmegged Samba to play himself one-on-one with Friedel, who he then beat with a low finish.
Blackburn woke up, and Roberts felt aggrieved that he did not win a free-kick on the edge of the box when he tangled with Martin Skrtel. He was further irritated when, moments later, Skrtel pulled him back and was only given a yellow card. Roberts and Blackburn thought a clear goalscoring opportunity had been denied and believed the Slovakian should have been sent off.
Liverpool were in danger of handing Blackburn a lifeline, and David Bentley went close with an audacious free-kick from over 30 yards out that flashed inches wide of Reina’s goal.
Rafael Benitez’s men had another penalty claim turned down when Brett Emerton slid in on Torres, but the former Atletico Madrid man had the last laugh when he headed Gerrard’s right-wing centre across Friedel and into the bottom right corner.
It was not only his 30th of the campaign but a seventh in seven matches at Anfield – the first time a player has achieved such a feat.
Substitute Voronin then got a rare goal in the last minute when he slid in to finish John Arne Riise’s low cross while Santa Cruz volleyed in a spectacular injury-time consolation goal after Skrtel failed to clear an aerial ball.
The victory consolidated Liverpool’s grip on fourth place, sending them five points clear of Merseyside rivals Everton.
Reda Maher / Eurosport