Full-time: Blackburn 0-1 Liverpool
Coutinho's strike aside, it certainly was not pretty from Liverpool but victory was vital in the aftermath of such a disappointing result against Arsenal.
They probably will not trouble the top four now, but a cup semi-final means their season is still alive.
Liverpool will meet Aston Villa in the last four at Wembley on April 19. Before that, however, they play Newcastle at Anfield in the Premier League next Monday.
Next up for Blackburn is a trip to Reading. The Royals are yet to secure their Championship status for next season, but have their own FA Cup clash to contend with against Arsenal.
So, a narrow win for Liverpool.
Blackburn defended valiantly for the most part, but were undone by a quality finish from Coutinho that followed lovely interplay between the former Inter Milan playmaker and Henderson.
It's been a memorable run from the Championship outfit, including two notable Premier League scalps, but they just came up short tonight despite Gestede's introduction giving them more impetus in the final third.
Blackburn 0-1 Liverpool
Well, what an ending that would have been.
Blackburn win a throw in line with the edge of the Liverpool penalty area, Spurr hurls it in and the ball finds its way to the feet of goalkeeper Eastwood who makes good contact with the shot but cannot beat opposite number Mignolet.
The full-time whistle sounds.
A penalty claim from Liverpool as Joe Allen is outmuscled by Williamson as he looks to work the space for a shot from the left-hand side of the box. Nothing given.
Four minutes of additional time has been signalled. Blackburn in the ascendancy now, looking to use Gestede as a target man at every opportunity.
Blackburn are being urged forward by a capacity crowd as a Marshall volley is blocked following good work from the powerful Gestede.
Sterling again looks to capitalise on the counter-attack, but his shot goes over.
A chance for Lambert to extend the lead just moments after coming on. Henderson floats a free-kick towards the back post, but the striker sends his header wide.
A late change for Liverpool as Lambert replaces Sturridge.
A little under 10 minutes remaining now and it's Liverpool who look to be heading to the FA Cup semi-finals at Wembley.
Blackburn have the firepower to get back into this, but at the moment they are being penned back deep in their own half of the pitch.
A brief break in play as Sterling is left in a heap after being handed off by Williamson as he raced up in support of Sturridge.
He is certainly not happy, but Friend is reluctant to dole out any punishment.
A second sub for Blackburn as centre-back Baptiste is replaced by Tommy Spur.
A chance for Sturridge to seal the victory as he collects a chipped pass from Sterling, moves past Alex Baptiste but sends his own lofted effort over the bar.
The angle was tricky, but that is still a real let-off for Blackburn.
71 minutes on the clock and we have our first goal of the evening. A Liverpool corner is initially cleared at the near post by Rhodes, before Henderson and Coutinho play a clever one-two that culminates in the latter smashing a low effort past Eastwood and inside the right-hand post.
Goal: Blackburn 0-1 Liverpool (Philippe Coutinho)
Gestede's arrival has already galvanised the hosts and his first contribution is to win a header for Rhodes, who strides forward but is eventually kept at bay by a block from Toure.
Liverpool attempt to break through Sterling after Mignolet punches away a cross, but the England international is felled by Evans near the halfway line.
The Blackburn midfielder is booked for his troubles and looks to have taken a knock.
That substitution looks a positive move from Blackburn's perspective, with Gestede moving into the final third to partner Rhodes.
Toure and Lovren will likely have a lot to contend with now, although a change in shape could leave more space in behind for Liverpool to attack.
64 minutes gone in the contest and Bowyer looks towards his bench for the first time. Gestede is the man to come on, replacing Conway.
Blackburn pour forward again as Marcus Olsson gets into the Liverpool box and asks for a penalty after being clipped by Johnson. Kevin Friend is unmoved.
Corry Evans has a shot comfortably saved by Mignolet.
A bit more noise reverberating around Ewood Park now as both teams begin to hit their respective strides.
Lovren comes close to making contact with a Henderson corner but Matthew Kilgallon clears in the nick of time.
The game is opening up a touch now, as Rhodes has a shot blocked and Liverpool captain Jordan Henderson almost breaks free before seeing the ball hastily booted away.
A bit more intent from Blackburn straightaway as Tom Cairney tests Mignolet with a shot from 25 yards that moves wickedly en route to goal.
Marshall comes agonsingly close to notching the opener from the resulting corner, but his thumping header is pushed on to the post by the Liverpool 'keeper.
The second half has kicked off. No substitutions for either side at the break.
A fairly attritional first half ends with no goals. Liverpool have been the dominant team, but they have struggled to carve out many clear-cut chances.
Blackburn, meanwhile, look compact and are defending in numbers, allowing preciously little space on the edge of their own box. Service to Rhodes has been in short supply, but they are having a lot of success in stifling the likes of Sturridge, Sterling and Coutinho.
Blackburn 0-0 Liverpool