GWANGJU, South Korea (Reuters) - Americans Caeleb Dressel and Regan Smith set world records in the semi-finals of the men's 100 metres butterfly and women's 200 backstroke at the world championships in Gwangju on Friday.
Dressel's new mark of 49.50 seconds shaved 0.32 seconds off Michael Phelps' 49.82 set at the 2009 worlds in Rome. The sprinter, who already has three gold medals in Gwangju, is set to swim in the 50 freestyle semis later on Friday.
Smith, 17, then gave the United States its second record of the evening when she swam 2:03.35 to take 0.71 seconds off compatriot Missy Franklin's mark set at the 2012 London Olympics.
(Editing by Toby Davis)
