Four more world records have fallen at the world swimming championships in Rome, bringing the tally for the week to 39 with one day remaining.
The American Michael Phelps broke his own mark in the 100 metre butterfly, beating Olympic rival Milorad Cavic of Serbia again.
Phelps stormed through the 50-second barrier in 49.82 seconds to beat Cavic by 13-hundredths of a second, coming from fourth at the 50 metre mark and overhauling Cavic in the final 25 metres.
Brazilian Cesar Cielo's triumph in the men's 50 metre freestyle made him the third man to complete the 50-100 metre free sprint double at the World Championships.
Zimbabwe's Kirsty Coventry nabbed her third straight 200 metre backstroke world title in a world record of 2:04.81, China's women won the 4x100 metre medley relay in a world record of 3:52.19 while one more world record fell in semi-final action, as Briton Liam Tancock clocked 24.08sec to lead the way into the final of the men's 50 metre backstroke.
Teenager Daniel Bell missed out on a semifinal spot in the final individual event for New Zealanders on the penultimate morning of heats, clocking a time just outside his national record in the 50 metre backstroke.
