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Nouioui got the visitors off to a great start when he connected with Charlie Mulgrew's cross to make it 1-0 after 10 minutes.
Swedish international Lustig doubled the advantage on 22 minutes, sliding in low to convert after Kris Commons's shot was saved by Hearts keeper Jamie MacDonald.
Stevenson then had the misfortune of putting into his own net after Mulgrew's centre caused problems for the home side.
A Celtic victory would take them three points clear of second-placed Inverness Caledonian Thistle.