The Reds were made to fight all the way by the Foxes at the King Power Stadium but eventually secured a visit to Huddersfield Town on a draining evening for the two sets of players.
Paul McGuinness' side were dealt a real blow when James Wilson twisted his ankle in training on Wednesday to join knee-injury victim Ashley Fletcher on the sidelines with Under-16 prospect Marcus Rashford instead pitched into a lone striker's role.
It was nip and tuck in the first half with the Reds enjoying spells of possession but rarely troubling the well-organised City backline. Macauley King was booked inside five minutes for a late tackle on Ben Barber but the hosts did not need to resort to aggressive tactics to keep United at bay.
Josh Harrop and skipper Andreas Pereira produced tame efforts before Joel Castro Pereira produced saves to thwart Kyle Bailey and Brandon Fox, with the latter a genuinely top-class stop after a right-footed screamer appeared destined for the net.
Callum Evans' inviting cross deserved a finish but it perhaps said much that the closest Red to it was fellow full-back Barber while Harrop spurned the clearest opening of the half, riding a foul challenge inside the box, but firing well off target. Andreas Pereira had a deflected attempt wide soon afterwards as Leicester were more accurate with their shooting with Matty Miles' snap-shot well held by Joel Castro Pereira.
Although United started the second period in attacking mode, Liam Sharpe was still not extended