Liverpool eventually saw off Cardiff to progress to the FA Cup fifth round on Sunday lunchtime, courtesy of three second-half goals.
Backed by their vociferous 6,000-strong away support Cardiff frustrated their illustrious hosts in the first half - although the Reds were far from their best.
Diogo Jota's individual brilliance almost gave Liverpool the lead inside four minutes, but he could only blast straight at goalkeeper Dillon Phillips from close range after nutmegging and turning his man in one fell swoop.
Cardiff felt they should have had a penalty just before the 20-minute mark when striker Mark Harris stepped across Ibrahima Konate and went to ground under the Frenchman's slightly clumsy challenge, but Liverpool survived a VAR review.
The visitors' only effort of note came midway through the half. Will Vaulks collected the ball on the break before cutting inside and firing a shot across Caoimhin Kelleher's goal, although it was not enough to worry the keeper.
Liverpool couldn't muster another clear-cut opportunity until the 34th minute. There was a neat interchange between Jota and Takumi Minamino before the former missed his kick and the loose ball rolled to Curtis Jones inside the box, but the midfielder conspired to lift his shot over the bar.
Roberto Firmino flashed a tricky header over two minutes later but that was it for the half as the whistle was welcomed by a huge roar in the away end.
Liverpool finally woke up after the break and assumed control of the game, but only after Kelleher survived another VAR check for denying a goalscoring opportunity AND serious foul play after coming flying out of his box and catching Harris on the calf in no man's land.
The hosts broke the deadlock when Jota headed Trent Alexander-Arnold's perfect free-kick delivery into the bottom corner, and that goal opened the floodgates.
New signing Luis Diaz and the returning Harvey Elliott were introduced to huge cheers shortly after the opener, and both would have an impact on the scoreline after Jota sent a volley just wide.
First, Diaz dispossessed a dawdling Perry Ng on the byline before showing quick feet and squeezing the ball into a dangerous area for Minamino to gleefully smash home. Then, Elliott was picked out by fellow substitute Andy Robertson in the box, controlling brilliantly before rifling a lovely finish beyond Phillips.
Young striker Rubin Colwill scored a fine consolation for the Championship side after Firmino was robbed of the ball in midfield, latching onto Isaak Davies' through ball and thumping a low strike into the back of the net.
It finished 3-1. Here's how the Liverpool players rated...
Liverpool player ratings
1. Goalkeeper & defenders
Caoimhin Kelleher (GK) - 5/10 - Untested in the first period but got himself booked for a wild challenge well outside his box in the first minute of the second. No clean sheet either.
Trent Alexander-Arnold (RB) - 7/10 - Had his full ball-playing repertoire on display. Got an assist with a perfect set-piece delivery for Jota.
Ibrahima Konate (CB) - 5/10 - Perhaps fortunate to survive a VAR review after a clumsy collision with Harris. Lost a couple of duels on the ground and aerially too.
Virgil van Dijk (CB) - 7/10 - Typically steady display, winning pretty much everything on the ground and in the air. Played forward as often as possible.
Kostas Tsimikas (LB) - 7/10 - Always an option in forward positions and put in countless tantalising crosses. Often let down by his teammates. Subbed with 20 to go.
Jordan Henderson (CM) - 7/10 - Grew into the match and began to dictate play in the second period, spraying intelligent passes around. Subbed.
Naby Keita (CM) - 4/10 - Tried to probe and create but very loose in his passing and shooting and too easily dispossessed. Subbed.
Curtis Jones (CM) - 6/10 - Saw lots of the ball but spurned a glorious chance before the break. Subbed soon after half-time as Liverpool changed shape.
Takumi Minamino (RW) - 7/10 - Worked hard and eventually got his goal. Subbed immediately afterwards.
Roberto Firmino (ST) - 6/10 - Dropped very deep to get involved, probably too deep. Battled hard but lost the ball for Cardiff's goal.
Diogo Jota (LW) - 8/10 - Turned and nutmegged his man in one fell swoop early on, but could only shoot straight at the keeper. How is this guy so good at heading? Perfect finish into the corner. Could have had another, but still great.
Harvey Elliott (CM) - 8/10 - Brilliant finish on his return from injury. Passing and movement were excellent, too.
Luis Diaz (LW) - 7/10 - Clever assist on debut. Turning, showing quick feet and putting the ball into a dangerous area. Picked up a nasty looking injury, but hopefully just impact.
James Milner (CM) - 5/10
Andy Robertson (LB) - 6/10 - Nice assist.
Thiago Alcantara (CM) - 5/10