Heaven had followed up his impressive performances against Arsenal and Real Sociedad with a relatively flawless opening 45 minutes in the East Midlands.
However, a painful-looking coming together with Foxes striker Patson Daka left the 18-year-old in agony early in the second half.
Sky Sports, who were broadcasting the game live in the UK, would not show replays of the incident and Heaven took five minutes to be helped off the pitch, as he was replaced by Toby Collyer.
Amorim doesn’t yet know the full extent of the issue and says Heaven will have to be checked over in the coming days.