The Astana pair are currently keeping out of each other's way at the Tour, with Nibali hunting stage wins from the breakaway and Aru battling for a high place in the general classification with his other seven teammates.
Nibali targeted, and won, the Giro d'Italia this year, with the aim of using the Tour de France to build up his fitness for the lumpy Rio road race.
Aru, meanwhile, may also be looking to challenge for the gold medal should his third week at the Tour de France be a success.
The pair's Astana teammate Diego Rosa will provide domestique duties, with a possible role as plan B should a breakaway get to the line.
BMC's Alessandro De Marchi and Damiano Caruso will make up the five-man team. Nibali will race the 59km time trial on the Wednesday following the road race alongside one other rider from the road race squad.
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