It was the result that the Mariners wanted or deserved, but it was a decent game for few fans that turned up to watch.
The Mariners battled well against the Premier League club's youngsters and went in ahead at half-time through a Moses Ogbu header.
But they were not to end their Northern Group A programme on a high as substitute Josh Eppiah brought the young Foxes level before scoring a superb winning goal in the last minute.
Town: Russell, Hewitt, Gibson, Davis, Pollock, Hessenthaler, Clifton, Robson, Rose, Cardwell, Ogbu.
Subs: Battersby, Hope, Ring, Cook, Painter, Starbuck, Vernam.
Leicester City: Johansson, Clark, Ughelumba, Johnson, Benkovic, Dewsbury-Hall, Thomas (C), Leshabela, Wright, Muskwe, Hirst.
Subs: Stolarczyk, O'Connor, Thomas, Leathers, Felix-Eppiah, Tee.
Referee: Sebastian Stockbridge
Attendance: 341 (22)