With Irving ruled out, the Nets will be without both of their superstars against the Sixers. All-Star forward Kevin Durant was already out due to the NBA's health and safety protocols.
Nets head coach Steve Nash said Durant would be allowed to return Sunday if he continues to test negative for COVID-19.
Durant ranks fourth in the league with 28.2 points per game, while Irving has averaged 27.1 points and 6.1 assists per game this season.
Brooklyn also will be missing guards Spencer Dinwiddie and Tyler Johnson and forwards Nicolas Claxton and Reggie Perry.
76ers guard Seth Curry is sitting out because of left ankle soreness.