Australia's Erika Yamasaki claimed the bronze in the 48-kg women's weightlifting event to win the first medal for the hosts, whose euphoria after a well-received opening ceremony on Wednesday was dampened by a possible drugs scandal involving its lifters.
Australian Sports Minister Rod Kemp said that unidentified tablets had been found along with syringes and vials in rooms occupied by home weightlifters at the Australian Institute of Sport in Canberra.
All the items were taken away to be tested, with the results possibly known later on Thursday.
Australian team chef-de-mission John Devitt warned against directly linking Australia's weightlifters to the discovery until the results of the tests were known, adding that athletes from other countries had also been at the world-renowned facility.
"It would be unfair to the competitors to start identifying them, zeroing in and saying these things are happening, until we get told what were the ingredients," Devitt told reporters.
CAFFEINE TABLET
Organisers have declared that the 4,500 athletes competing in Melbourne could expect one of the toughest anti-doping blitzes ever, with almost one in four to be tested.
In another setback for the hosts, Australian team officials were forced to admonish marathon runner Scott Westcott for saying he would probably take a caffeine tablet before Sunday's race.
While not banned, the use of caffeine is still monitored by the World Anti-Doping Agency.
There was better news in the pool for the Australians, who have topped the medal count at the past four Games and are hoping to better their record haul of 202 medals from Manchester.
"I have absolute confidence in our swim team and in our sport that we are drug free," head swim coach Alan Thompson declared as Australian sport began another round of doping soul-searching.
Libby Lenton eased into her first final with a conservative swim in the women's 200 metres freestyle heats at the start of her bid for seven gold medals.
Australia's Craig Stevens, a late replacement for Ian Thorpe, qualified quickest for the men's 400m freestyle final and Brooke Hanson was quickest in the women's 200m individual medley.
England's Liam Tancock set a Games record in the men's 50m backstroke, clocking 25.26 to reach the semi-finals.
Queen Elizabeth visited the swimming before leaving Australia as athletes from 71 associations representing 53 countries got down to business on the first day of competition.
