"If Murat had not lost sight of the Russians?"

 At the time of the invasion of Moscow Miloradovich negotiated with Murat to ensure the safe retreat of two Russian regiments that were in danger of being trapped by the French army. Murat's general Sebastiani pulled his cavalry back in order to let them escape to the south, but Murat then lost contact with Miloradovich's rear guard, allowing the Russians to make a sudden turn to the west whilst fooling Murat into chasing them towards the south-east. Through these actions Kutuzov's army was well placed, come the French retreat from Moscow, to force Napoleon's army to withdraw along the same route they had recently advanced, which was largely devastated, rather than moving to other roads that would have refreshed their provisions.