Following a goalless first half at LCFC Training Ground, the Italian giants took the lead 10 minutes after the interval; 19-year-old Luca Amaradio finding the net for the visitors.
Their advantage lasted less than a minute, however, as Kian Pennant equalised for the Foxes, assisted by Kevon Gray.
Pennant's goal wasn't enough for a share of the spoils.
Diego Pugno soon re-established the lead and that's how it stayed in Seagrave, with the Old Lady claiming all three points in the group stage opener.
The Foxes youngsters will also face Group B opponents Valencia B, Borussia Monchengladbach II and Nordsjaelland Under-21s in the European competition, with Valencia up next at home on Tuesday 23 September.
Mirsad Ali received a nominated for August's Premier League 2 Player of the Month.
Before then, the side coached by Leon McSweeney head to Wealdstone in the National League Cup on Tuesday 16 September, prior to hosting Tottenham Hotspur Under-21s three days later (all 7pm kick-offs).
The details...
City: Donohue, Aluko (c) (Amartey 60'), Gray, Khela, Ali; Neale, Golding (Onanaye 90'); Briggs, Fisken (Carr 75'), Otchere (Hutchinson 75'), Pennant.
Unused subs: French, Aideed, Omobolaji.
Goal: Pennant 56'.
All times BST.