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.
Tweets of the week: Did Geraint Thomas run over a small child?
Also featuring Patrick Lefevere, Alex Dowsett and Rigoberto Urán
By Jonny Long •
'I had thoughts of just packing it all in': Gabriel Cullaigh's lonely experience and rejection with Movistar
The Yorkshireman explains why he was unable to deliver on the promise he showed at U23 level
By Chris Marshall-Bell •