AIS scholarship holder Anna Meares has launched a medal offensive for Australia on day one of the 2009 UCI Track Cycling World Championships in Pruszkow, Poland with silver in the 500m time trial.

Meares opened Australia's medal tally with a silver medal ride in the 500 metre time trial. Meares, 25, went into the event as the World Record holder and it took a World Record to beat her.

She missed last year's event after breaking vertebrae in her neck and has only been back on the bike for three months since her post Olympic Games break so she found herself seeded as the fifth of 22 starters to line up.

Meares, who won gold in the event at the Athens Olympic Games and was disappointed when it was dropped from the program for Beijing, came out with all guns blazing to cover the distance in 33.796sec.

She then faced an agonising wait to see if she time would be enough to reclaim her World Champion's rainbow jersey.

The 22nd rider to start was Simona Krupeckaite from Lithuania who is the only other woman to have ridden under the 34 second barrier and she proved why tonight with a blistering ride that was faster than Meares at every half lap time check. Across the line Krupeckaite stopped the clock in 33.296 seconds to lop three tenths off Meares' the mark of 33.588 seconds set by Meares in Spain in 2007.

'I'm actually really pleased with my performance because I was going to be more than happy with any sub 34 I rode here today - that was my goal,' Meares said.

'I'm not sure if you saw my reaction to Simona's ride but my mouth dropped about a foot (because) that is sensational time, a great ride to her and, as heartbreaking as it is to see my World Record go, it's great for women's sprint cycling.

'It wasn't so long ago they thought you couldn't break the 34 second barrier but looking at tonight I think we'll see women break the 33 second barrier (and) that's just an extra incentive for me in the next couple of years to really knuckle down and get it back.'