West Ham United's U23s were on the wrong end of a 3-1 defeat against Leicester City at the King Power Stadium on Monday.
Terry Westley's men were previously unbeaten in Premier League 2 Division 1 but goals from Kelechi Iheanacho, Vicente Iborra and George Thomas put the hosts in control.
Toni Martinez pulled one back late on but the Foxes held on to take all three points.