The grand prix was shaved by a lap on Saturday to 26, with riders ordered to change bikes with fresh tyres mid-race at the newly re-surfaced track in a first for MotoGP.
Tyre provider Bridgestone said on Sunday it was unable to guarantee the safety of their rear slick tyres beyond 10 laps and it was decided to shorten the race to 19 , Race Direction said in a statement.
Riders would be required to enter the pits and change to their second bike with fresh tyres at least once during the race.
"In normal circumstances this means that the rider must change machines only at the end of lap nine or lap 10," the statement said.
Rain appeared unlikely as Phillip Island basked in sunshine on a warm, spring day, but officials said the race would be red-flagged if it became wet.
"The restarted race will be for the number of laps required to complete 19 laps, but with a maximum of 10 laps and a minimum of five laps," the statement added.
The late changes will add further intrigue to the championship battle between pole-sitter Jorge Lorenzo and championship leader Marc Marquez, who is second on the grid.
Honda-riding rookie Marquez can seal the MotoGP championship two races early with victory at Phillip Island if Yamaha's title-holder Lorenzo finishes no higher than third.
KTM-riding Spaniard Alex Rins won the Moto3 category ahead of second and third-placed compatriots Maverick Vinales and Luis Salom.