Barcelona:Matt Welsh and Leisel Jones of Australia, and Japan's Kosuke Kitajima all set world records on the second day of pool action in the world swimming championships in Barcelona. Welsh, best known as a world champion backstroker, shaved 0.01 seconds off compatriot Geoff Huegill's men's 50 metres butterfly world mark, clocking 23.43 in a major upset victory from the outside lane number eight. He had been the slowest qualifier for the final. Another mark to be broken was by 17-year-old Liesel Jones, Olympic silver medallist in 2000 and silver medallist at the last world championships. She clocked one minute 6.37 seconds in the semi-finals of the women's 100m breaststroke to beat the 1:06.52 mark set by South Africa's Penny Heyns in 1999. Jones wept with joy when she heard the sound effect of breaking glass -- used over the public address system at the tournament to indicate when records are broken. Kitajima, surging ahead late in the race, also set a world record on his way to winning the men's 100-metre breaststroke. The feisty 20-year-old Japanese clocked 59.78 seconds in the finals, shaving the previous record held by Russia's Roman Sludnov by 0.16.