Mobil 1 Boost Mobile Racing’s James Courtney will miss all of today's running at the Winton SuperSprint.
The 2010 champion had been due to contest Practice 1 and Practice 2, but is ill and has returned to the team's hotel.
Courtney will be replaced by his PIRTEK Enduro Cup co-driver Jack Perkins.
Perkins drove the #25 Commodore on Friday morning in the additional driver session, essentially for co-drivers, setting the 16th-fastest time in wet conditions.
He will stay in the car for the pair of 45-minute sessions, while Scott Pye jumps into his sister ZB Commodore.
Pye’s co-driver Warren Luff finished at the foot of the times in the first session, limited to six laps by a cooling problem.
After 12 races in the 2018 Virgin Australia Supercars Championship, Pye and Courtney are sixth and seventh in the standings.