Great Britain had to settle for a silver medal in the men's team pursuit after failing to defend their title on the opening day of the World Track Cycling Championships in Belarus.
The British quartet of Ed Clancy, Steven Burke, Andy Tennant and Sam Harrison finished more than four seconds behind Australia, who took gold in three minutes and 56.751 seconds.
Earlier, young duo Becky James and Vicky Williamson picked up Britain's first medal in Minsk with a bronze in the women's team sprint.
And Kian Emadi, 20, only missed out on a medal in the men's 1km time trial by 0.306 seconds in the first World Championships since the London Olympics.
An unfamiliar British squad for the first World Championships since the London Olympics, included six debutants as the preparations start for the Rio Games in 2016.
In the absence of sprint stars like Victoria Pendleton, who has retired, and Sir Chris Hoy, who is taking a break from the sport, British Cycling's performance director Dave Brailsford called his squad "the changing of the guard".
Despite missing out on a gold on day one, he will have been encouraged by their opening results.
Britain's men, who have triumphed at the last two Olympics in the 4km or 16-lap race, included Clancy and Burke - both part of that London line-up, while Tennant and 20-year-old Harrison came in for Geraint Thomas and Peter Kennaugh.
Australia are also rebuilding for Rio, arriving without Jack Bobridge or Rohan Dennis - both key members of the squad that took silver at the Olympics.
The two teams were only 0.459 seconds apart in qualifying, with Australia fastest into a final they led from start to finish. Britain clocked a time more than a second slower than they managed earlier in the day and their performance in the final was far more disappointing than the actual result.
Clancy told BBC Sport: "Of course it is disappointing, but this is the first stage in an Olympic cycle.
"It is part of a long process with new face in the team and we are in a better position than we were at the start of the last Olympic cycle in 2009."
Burke added: "We gave it our all and I thought Sam rode terrifically well for his age and I think that we did fairly well overall. At the 2009 World Championships we came fourth, so that is two places better."
There was plenty to smile about for James, 21, and Williamson, 19, who were trying to fill Pendleton's shoes and established British sprinter, Jess Varnish, who has a back injury.
In qualifying and in the bronze-medal final, they trailed Australia after the first lap but turned the result around thanks to a powerful final lap from James, clocking 33.893 seconds to take third behind Germany and China.
Emadi, who will go as man three in the sprint on Thursday, clocked one minute 1.756 seconds on his debut in the kilo and led with five men of the 19-strong field to go. He was in bronze medal position until the final lap of the final rider, with New Zealand's Simon van Velthooven pipping him to the podium.
France's Francois Pervis took gold in 1.00.22, with Van Velthooven taking silver and Germany's Joachim Eilers winning bronze.
"I'm definitely happy," said Emadi. "It's a great experience to come here and I gave it my best.
"It would have been nice to have got a medal but it is about the performance and I am happy with that."