Rafa Benitez handed youngsters Jack Hobbs, Nabil El Zhar and Sebastien Leto their chances to impress as Robbie Fowler returned to Anfield with his new club.
Ryan Babel started up front alongside Peter Crouch, while Brazilian starlet Lucas partnered Steven Gerrard in midfield.
BBC Sport Report
Steven Gerrard spoiled former team-mate Robbie Fowler’s Anfield homecoming with Liverpool’s winner to end Cardiff City’s Carling Cup hopes.
Nabil El Zhar gave Liverpool the lead in this fourth-round tie with a long-range thunderbolt on 48 minutes.
Cardiff captain Darren Purse equalised, heading home Paul Parry’s free-kick.
But within 46 seconds Liverpool retook the lead as Yossi Benayoun raced clear on the left and laid the ball into Gerrard’s path to strike home.
Fowler, still a favourite with the Liverpool fans, returned to Anfield in the blue of Cardiff after leaving for the second time last summer.
The 32-year-old’s name echoed around the stadium before the start, and four minutes into the match Fowler had a great chance to score.
Fabio Aurelio tripped the striker just outside the box in front of the Kop and Fowler, with a two pace angled run-up, sent a curling free-kick towards the top corner.
But French goalkeeper Charles Itandje flung himself to his left to claw the ball away to deny Fowler a dream return.
Liverpool responded with a Ryan Babel effort – clipped over the bar as he fell – before a clever, nimble turn from Peter Crouch ended with a low drive which fizzed wide.
Aurelio was next to try his luck with a bending drive that Bluebirds goalkeeper Michael Oakes comfortably turned round a post.
Lucas Leiva and Sebastian Leto also both went close for the home side, while at the other end Itandje turned away a dangerous Parry header, but the match remained goalless at the break.
Three minutes after the restart El Zhar remedied that, with a wonderful 30-yard strike to record his first Liverpool goal.
Gerrard made the early inroads with a typical driving run, before picking out El Zhar in space.
The 21-year-old Moroccan international, bought from St Etienne, came inside onto his right foot and unleashed a pile-driver that fizzed past Oakes and went in off the inside of the post.
Joe Ledley, who had been bright all night, almost pulled Cardiff level but the Wales international saw his goal-bound shot picked off by Itandje.
On 65 minutes Parry then sent across a fine bending free-kick that Cardiff skipper Purse honoured with an equally good header to level the score.
But Liverpool restored their lead within a minute as Gerrard swapped passes with Benayoun before burying the ball in the net from 15 yards.
Crouch nearly gave the Reds the comfort of a cushion but Oakes was again alert to palm the towering striker’s header away.
Fowler nearly wrote himself a story-book ending with a vintage turn and snap-shot, only for the ball to ricochet off a Liverpool defender.
Then in the last minute Parry found space for a goal-bound effort, but again desperate defending saw the shot blocked and with it went Cardiff’s last chance of forcing extra time.
Liverpool could even have finished with a flourish as Harry Kewell broke away on a swift counter-attack in injury time, only for Benayoun to blaze wide.
Liverpool: Itandje, Arbeloa, Hobbs, Carragher, Aurelio, El Zhar (Kewell 71), Lucas (Mascherano 87), Gerrard, Leto (Benayoun 63), Crouch, Babel
Subs Not Used: Martin, Riise
Booked: Lucas, Babel
Goals: El Zhar 48, Gerrard 66
Cardiff: Oakes, McNaughton (Gunter 84), Purse, Johnson, Capaldi, Ledley, Rae, McPhail (Whittingham 89), Parry, Fowler, Hasselbaink (Thompson 75)
Subs Not Used: Magennis, Loovens
Goal: Purse 65
Referee: Peter Walton (Northamptonshire)