Ben Simmons faces the biggest game of his brief NBA career when the Philadelphia 76ers attempt to avoid being eliminated from the playoffs by the Toronto Raptors.

A bad result will lead to more calls for the 76ers to trade the Australian 22-year-old and for head coach Brett Brown to be axed.

Simmons has been hit with a barrage of criticism from Philadelphia fans, US media and former NBA stars including Charles Barkley after the 76ers lost the past two games against the Raptors to fall just one loss away from the end of their season.

The Raptors lead the series 3-2 with game six in Philadelphia on Thursday (Friday 10am AEST).