With referee Mike Riley also awarding a penalty as a double punishment for Blackburn, Danny Murphy beat Brad Friedel from 12 yards to put Liverpool back in the game.
Rovers by this time were already in the lead after an impressive opening 35 minutes, with the recalled Dwight Yorke rising highest to meet David Thompson's right-wing cross and head past a stranded Chris Kirkland to underline their superiority.
Unfortunately for Blackburn, the sending off proved to be the game's turning point.
A minute after the break, Emile Heskey missed a sitter when looking suspiciously offside but duly scored three minutes later from an El Hadji Diouf cross to put the Reds ahead.
Twelve minutes later, Heskey was on target again from another Diouf centre and Blackburn looked sunk.
Heskey then squandered a penalty after substitute Harry Kewell was felled by Vratislav Gresko, with Friedel denying the Liverpool striker a hat-trick.
The Reds did get a fourth on 79 minutes when Kewell was picked out by Diouf to score, but Graeme Souness' Blackburn side refused to lie down and die.
Indeed, just two minutes later, the impressive Barry Ferguson got on the end of neat passing from Brett Emerton and Yorke to fire home his first goal for Rovers.
And Yorke gave the Blackburn fans something extra to cheer when he grabbed his second goal of the night from close range in the dying seconds.
But it proved to be too little to late for Rovers as the holders advanced to the fourth round.