Nankervis has suffered a syndesmosis injury to his left ankle and will join Tom Lynch (broken foot) and Jack Graham (hamstring) on the sidelines.
The Tigers expected Nankervis, 28, to be sidelined for the "medium term", which is likely to be at least several weeks.
Lynch suffered a foot fracture in the second quarter of Saturday's five-point loss but played out the game.
The gun forward, who will also face the AFL tribunal for his aerial bump on Alex Keath, will undergo surgery and the Tigers will reassess the injury before putting a timeline on his return.
Graham injured his hamstring in the second quarter.
Nankervis' absence also gives Richmond a serious ruck headache.
Unless Ivan Soldo returns from the foot injury that has sidelined him for the opening rounds of the season, young ruck-forward Samson Ryan will have to shoulder the load against Sydney's Peter Ladhams and Joel Amartey.
The Tigers could call on defender Ben Miller for support while Marlion Pickett has frequently been used as a pinch-hitter.
Project ruckman Mate Colina is sidelined long-term with a back injury.
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