Following the second rest day, the stage travelled to Romans-sur-Isère, where Aru finished in 18th place.
Aru will have a chance to fight for his first Tour win over three-time and defending champion Froome in two mammoth mountain stages on Wednesday and Thursday.
The Italian star will have to perform his best in the mountain climb as the penultimate stage, a time trial around Marseille on Saturday, favours the Briton.
Wednesday's stage 17 will take the riders over the fearsome 2,642-metre Galibier peak where Aru is sure to attack, closing with a 28-kilometre descent to ski resort Serre Chevalier.
Thursday's stage 18 offers the final summit finish against the dramatic backdrop of the Col d'Izoard at 2,360 metres.
The Tour ends with a ceremonial run-in to Paris on Sunday.
With ANSA