Athletes face out-of-competition drug tests as late as the evening before their events at the Sydney Olympics.

"We do not want to test the athletes on the day (of the start of their events), but we will test athletes up to the evening prior to the day of competition," IOC medical commission chief Patrick Schamasch said.

Olympic 100-metres champion Donovan Bailey said he had been woken up on the night he arrived in Australia to provide a urine sample.