Getting another win in such a short space of time--particularly with nearly all of the same personnel involved--was always going to be a big ask, and in the end Liverpool didn't have the energy or creativity to break down a stingy Blackburn defense. The visitors had only a few bright spells in the match, mostly looking to shut the match down and secure a replay. By that standard, it was a victory for Gary Bowyer's side, and they'll feel good about their chances at getting a result in front of their home supporters.
With Joe Allen injured and Mamadou Sakho presumably not match fit, Brendan Rodgers brought Emre Can into the midfield and Glen Johnson into Liverpool's three-man back line, and selection problems were compounded by the early injury to Martin Skrtel. The Slovakian was off after three minutes with a nasty-looking concussion, and without cover in midfield off the bench beyond teenager Jordan Williams, Rodgers was forced to bring Kolo Toure on centrally.
And despite the fact that they secured another clean sheet, it wasn't the prettiest day for the Liverpool defense, as they looked far more scattered without Skrtel and Can. It was a somewhat similar story in the midfield, where Can wasn't near his best and struggled to combine with Jordan Henderson. Nothing doing at the front end aside from a few chances from set pieces and some positive play near the end from Mario Balotelli, with Daniel Sturridge struggling for impact and neither of Adam Lallana nor Philippe Coutinho able to get anything going.
It was the performance of a tired side, both mentally and physically, one who couldn't find any inspiration or different ideas to break down a resolute opposition. Liverpool did what was needed defensively in denying Blackburn any threat, with Simon Mignolet saving their best chance from a corner with a sprawling save, but going forward they had few ideas and lacked the cutting edge they've largely had in spades in recent weeks.
They might not have needed it if Andre Marriner granted one of at least two penalty appeals, the first of which seemed clear as Adam Lallana was bundled over in the first half. Daniel Sturridge was later dragged down twice, and Balotelli found himself pulled down as well at one point. No sense complaining, as Liverpool's form in recent weeks has indicated that they're more than capable of getting a win regardless of the opposition, but Marriner's decisions (or non-decisions, as it were) added to frustrations.
Liverpool are still in the competition, though, and they'll now have eight days off for rest and recovery before they travel to Swansea City in the Premier League. A win here was obviously preferable, as it would have secured the objective and left them without another match to play between crucial league fixtures against Manchester United and Arsenal. But with a squad nearing full fitness, hopefully they'll be able to cope, and this one will prove a very minor setback as they work toward silverware and securing a top four finish.