The reds overcame a damp October evening in Lancashire to maintain a long unbeaten record and advance to the last eight of the League Cup.
A much changed reds side, featuring two players receiving their starting debuts, may have considered themselves lucky to get to half time 0-0. However, a tweak of the formation in the second half saw the reds overcome the Championship side - goals from Takumi Minamino and Divock Origi.
Joe Gomez and Joel Matip started in defence, with Neco Williams replacing Trent at right back.
18 year old youngster Harvey Blair made his debut, with Tyler Morton making his first senior start - he played the second half in the previous round of the cup.
Alongside Oxlade-Chamberlain and Curtis Jones, Morton had struggled to put a stamp on the first half. Harvey Blair too will have been disappointed not to see more of the ball in his period on the pitch.
Adrián, Gomez, Matip, Tsimikas, Williams, Morton, Jones, Oxlade-Chamberlain, Blair, Minamino, Origi
Subs: Pitaluga, Hughes, Konaté, Firmino, Jota, Dixon-Bonner, Beck, Phillips, Bradley
In fact, the reds were lucky to stay level after Adrian was called into action more than expected in the opening 45 minutes. At one point, he was called in to stop a save and from the rebound, Neco Williams had to stop a shot with his face at the back post.
At half time Matip was replaced by Nat Phillips - a decision based more on bringing Joel Matip back to match action slowly rather than anything tactical.
However, 10 minutes later Conor Bradley was brought on to replace Harvey Blair. The youngster slotted in at right back, allowing Neco Williams to move further forward and the Welsh international was involved in both Liverpool goals.
He created the chance for Takumi Minamino to add his 7th goal of his LFC career.
And with 5 minutes remaining Neco's shot spilled into the path of Divock Origi who put the game beyond Preston. An outrageous, quick reaction backheel to seal the game. Kostas Tsimikas starting the move that led to the second goal.
The reds are now undefeated in 23 games, stretching back to April this year.
The draw for the last 8 is made on Saturday.