Martin, who comes to Australia 18 points adrift of title rival Francesco Bagnaia after his crash in Indonesia last weekend, set the pace in Friday morning's opening 45-minute session with a best time of 1m29.039s.
The Spanish rider commanded the timesheets for almost the entire session, becoming the first man to break the 90-second barrier with a 1m29.882s that remained unbeaten until the final few minutes.
