The fact Arne Slot felt the need to throw on Ibrahima Konate, Florian Wirtz and Hugo Ekitike on the hour mark summed up exactly how much Barnsley pushed Liverpool.
When Jeremie Frimpong made it 2-0 in the first half, Liverpool should have coasted to victory, but Dominik Szoboszlai's calamitous error gave the Tykes a sniff and led to a nervous second half for the home fans.
The hosts were far from convincing and Anfield was on edge until Wirtz restored the two-goal advantage in the 84th minute.
In the end, the difference in class showed, with the first three Liverpool goals coming from real moments of individual quality.
The link up between Wirtz and Ekitike after they came on was definitely encouraging to see for Slot and Liverpool supporters, but this was a night when Conor Hourihane's side could take plenty of pride.
Until the 84th minute, this cup tie was well in the balance.
