[gallery size="medium" td_select_gallery_slide="slide" td_gallery_title_input="Hosszu claims 2nd gold" ids="75542,75541,75540"] RIO DE JANEIRO — Katinka Hosszu of Hungary won the women's Olympic 100 meters backstroke Monday to claim her second gold of the Games, edging out Kathleen Baker of the United States as doping hostilities worsened in Rio. Canada's Kylie Masse and China's Fu Yuanhui tied for bronze, with the top four separated by just 0.31 seconds. Australian world champion Emily Seebohm, swimming in an outside lane, set the early pace but Hosszu powered her way through the field in the last half of the race to touch the wall in 58.45 seconds. Baker, who qualified fastest for the final, clocked 58.75, to finish 0.01 seconds ahead of Masse and Fu. It was a second gold in Rio for Hosszu, the self-styled 'Iron Lady' of swimming, after her world record-breaking victory in the 400 individual medley on Saturday. Hosszu, who is also swimming in the 200 backstroke, butterfly and medley, had come away empty-handed from three previous Olympics, despite winning five world championships titles. Olympic legend Michael Phelps backed young teammate Lilly King in speaking out against dope cheats after she vanquished drug-tainted Russian Yulia Efimova for Olympic 100m breaststroke gold. "I think you're going to see a lot of people speaking up more," said 19-time Olympic gold medalist Phelps. "I think she's right, something needs to be done." King, a 19-year-old first-time Olympian, had made it clear she didn't think Efimova belonged in the pool after serving a 16-month ban in the wake of a 2013 positive test and a positive test this year for meldonium. Plenty agreed as the 24-year-old world champion from Russia was showered with boos as she took to the blocks. King led at the turn and repelled a late Efimova charge to win in an Olympic record of 1min 04.93sec, with the Russian second in 1:05.50. American Katie Miele was third in 1:05.69. "For me it's very hard to swim today, this is like three weeks of crazy," said Efimova, who broke down in tears facing journalists after the race. It was in contrast to the celebrations of China's Sun Yang, another swimmer targeted by his peers for past drugs transgressions. Sun shook off controversy to win the 200m freestyle gold, cheered on by Chinese teammates and supporters in the stands, one group of them seated behind a section of Aussies whose 400m free gold medalist Mack Horton this week branded Sun a drugs cheat — a reference to his three-month suspension in 2014 for a positive test for a banned stimulant. Third at the 150-meter mark, Sun stormed past early leader Chad le Clos of South Africa to win in 1:44.65. Le Clos settled for silver in 1:45.20 with American Conor Dwyer third. Ryan Murphy gave the US a second gold on the night, extending America's run of dominance in the men's 100m backstroke, coming from fourth at the turn to win in an Olympic record of 51.97sec and become the sixth straight US Olympic champion. China's Xu Jiyau was second in 52.31 and American David Plummer captured bronze in 52.40. China's Lin Yue and Chen Aisen won gold in men's 10m synchronized diving. Steele Johnson and David Boudia of the United States took the silver medal. Britain's Thomas Daley and Daniel Goodfellow won bronze, edging out a German duo on their last dive.