By Nick Mulvenney
RIO DE JANEIRO (Reuters) - Brianna Rollins gave the United States its first track medal of the Rio Olympics when she won the 100 metres hurdles final on Wednesday, leading compatriots Nia Ali and Kristi Castlin across the line for an American podium sweep.
Favourite Rollins, who owned the fastest personal best in the field, ran an almost error-free race from lane six to add Olympic gold to her 2013 world title by a couple of paces in 12.48 seconds.
Ali was clear in second place when she crossed the line to take silver in 12.59 but Castlin, who was fourth over the final hurdle, faced a nervous wait before discovering she had done enough in the dash to the finish to take bronze in 12.61.
The American trio shrieked in delight and jumped up and down on the track in an embrace when the scoreboard confirmed they had secured the first Olympic podium sweep in the women's sprint hurdles.
"Oh my God, it's a relief," said Rollins. "There has been such a lot of anticipation. I have younger brothers and as the oldest I like to lead by example... even from far away."
The sweep was all the more remarkable given world record holder Kendra Harrison and 2008 Olympic champion Dawn Harper missed the Games after failing to make the cut at the U.S. trials.
Cindy Ofili, who was also born in the United States but elected to run for Britain, pushed Castlin right to the line with her best run of the year but lost out on a medal by two hundredths of a second in 12.63.
European champion Cindy Roleder of Germany was quickest out of the blocks but had to settle for fifth in 12.74, ahead of Pedrya Seymour of the Bahamas, who set a national record in the semis and was going well until she hit the penultimate barrier.
Ofili's sister Tiffany Porter, also American-born but racing for Britain, was seventh with Canada's Phylicia George finishing last.
Rollins's triumph put the United States top of the medals table in the athletics at the Rio Games with five gold medals and 19 in total, ahead of Kenya and Jamaica on both counts.
Harrison and Harper were not the only notable absentees with world champion Danielle Williams failing to get through the Jamaican trials and Australia's Olympic champion Sally Pearson forced to withdraw from the Games with an injury.
(Editing by John O'Brien)