Abe was denied his hat-trick on two occasions by Cristiano Dzialuk early in the second period, with La’more Lee Forrester also frustrated by the goalkeeper.
Derby went close to levelling twice. Kacey Myers could not hit the target from close range and Mintus curled onto the crossbar.
But the game appeared to be beyond them as a result of a two-minute spell that saw them concede a third and have Mintus sent off.
O’Connor restored the Reds’ healthy advantage, converting the rebound of a Forrester strike that had been saved by Dzialuk.
Bernard then matched an attempt from Euan Griffiths just seconds before Mintus received his second yellow card.
Derby, however, clawed themselves a lifeline when Clarke carried the ball from the halfway line and kept his composure to finish from close range.
It set up a nervy finale – which included a disallowed leveller, Simeon Fearon striking the post and Bernard pulling off a save – but Sonni-Lambie’s tidy goal made sure of the win with 90+9 on the clock.
Team
Liverpool U18s: Bernard, Hickman, Ayman (Powney Wain, 60), Cisse (Murray-Holme, 46), Clarke, Upton (Owen, 46), Abe (Sonni-Lambie, 60), Eden, Lee Forrester, Farkas, O’Connor.
Unused sub: M. Wright.
Next up
The young Reds travel to Slovakia on Tuesday to face MSK Zilina in the UEFA Youth League’s Round of 32.
The one-legged tie kicks off at 3.30pm GMT and will be shown live on All Red Video.
