Britain's Aileen McGlynn and Helen Scott had to settle for Paralympic silver in the women's blind and visually impaired time-trial at the London 2012 velodrome as Australia won gold.
McGlynn and Scott clocked one minute 09.469 seconds, but Australia's Felicity Johnson and Stephanie Morton were last on the track and stole victory by 0.550secs in a Paralympic record of 1min 08.919secs.
It was the first time McGlynn has tasted Paralympic defeat in the event after the 39-year-old from Glasgow won gold in Athens and Beijing with Ellen Hunter as pilot.
McGlynn and Scott finished second to the Australian pair at the World Championships earlier this year and were runners-up once more.
New Zealand's Phillipa Gray and Laura Thompson claimed bronze in 1:11.245, with Britain's Lora Turnham and Fiona Duncan fourth in 1:11.479.
Mark Colbourne qualified fastest in the men's C1 individual pursuit in a world record of 3:53.970.
Colbourne finished second to Li Zhang Yu in the C1-2-3 one-kilometre time-trial on day one and watched the Chinese rider set a world record of 4:00.235 in 3km pursuit qualifying before improving the mark himself.
The 42-year-old Welshman was set to meet Li in the race for gold on Friday afternoon.