DOHA — Brazil set a world record to win the men's 4x50-meter medley relay final on the second day of the Short-Course World Championships Thursday, improving a mark that had been set hours earlier by Russia. Brazil's quartet of Guilherme Guido, Felipe Franca Silva, Nicholas Santos and Cesar Cielo finished in 1 minute, 30.51 seconds to take the gold and shave more than two seconds off the world record Russia set in the morning heats at Hamad Aquatic Centre. This was the first time the event was staged at the worlds. France was second in 1:31.25, the United States third, and Russia fourth. Hungary's Katinka Hosszu broke the women's 100-meter backstroke world record en route to winning. Hosszu, known as the “Iron Lady,” finished in 55.03 seconds, surpassing the record of 55.23 set by Shiho Sakai of Japan in Berlin in 2009. Emily Seebohm of Australia took sliver in 55.31. Chad le Clos joined in the fun as the South African broke another world record in the men's 100 butterfly. The world swimmer of the year won in 48.44 seconds, shaving .04 seconds off the mark set by Russian Evgeny Korotyshkin in Berlin in 2009. Tom Shields of the US was second in 48.99. On Wednesday, Mireia Belmonte Garcia broke records in the 200m butterfly and 400m individual medley followed by the efforts of the Netherlands women's 4x200m freestyle relay in the final event of the first day. The 24-year-old Garcia became the first woman to break two minutes in the 200 butterfly as she tracked Hosszu the entire race before producing a stunning final turn and swimming away from the Hungarian. Belmonte touched in one minute, 59.61 seconds, more than 1.5 seconds ahead of Hosszu, who has dominated the short-course events in 2014. It was the first world record of the championships in the Qatari capital, though the Spaniard had little time to savor the moment before she was back in the pool 40 minutes later for the 400 individual medley final. The Dutch women rounded off the record-breaking session when they clocked 7:32.85 for the relay, shattering the mark set by China in 2010 by more than three seconds. France's men won the 4x100 freestyle title. — Agencies