Liverpool haven't had much reason to pay anything other than cursory attention to Manchester United in recent seasons.
But the last few weeks have seen all eyes on Old Trafford - and the team line-ups in particular.
Certainly, United boss Ole Gunnar Solskjaer irked Liverpool supporters by making good on his promise that "someone might not be happy" with his selection this week, fielding an effective reserve team that went down 2-1 to Leicester City on Tuesday to deal a major blow to the Reds' Champions League qualification hopes.
And it was the sight of supporters lining up in goal, left-back, right wing, up-front and just about every inch of the Old Trafford pitch that forced the postponement of last Sunday's visit of Liverpool and prompted United's fixture pile-up.
Klopp, for his part, had every sympathy with Solskjaer's plight.
But might the Reds boss be about to flummox United with his own surprising selection call?
After all, he has already done it before against their bitter North West rivals.
Amid all the confusion at Old Trafford earlier this month, it's easy to forget both teams initially carried on regardless and confirmed their line-ups an hour before the expected 4.30pm kick-off.
And featuring at centre-back was Nat Phillips, despite missing the previous two games with a hamstring complaint and having seemingly been ruled out of the game by Klopp just days earlier.
It wasn't what anyone was expecting.
Now, with the rescheduled game taking place this evening, Klopp has concerns over another centre-back as Ozan Kabak struggles for fitness.
Rhys Williams is on standby to deputise as he did in Saturday's win over Southampton, while moving Fabinho back from midfield is another option.
Klopp has already indicated Kabak is out, the defender not spotted in training on Tuesday. That, though, may be just to put Solskjaer off the scent.
Will the Turkey international make it? Will there be a midfield switch? Could there be a change in the attack?
We will only know around 7.15pm tonight. Nobody, though, should be surprised if Klopp throws another curveball.
