Australia's 2012 Olympic champion Sally Pearson's bid to put behind her two years of injury hell got off to a good start on Friday as she coasted into the 100 metres hurdles semi-finals.
The 30-year-old -- the 2011 world champion -- missed both the 2015 world championships and 2016 Olympics because of serious injuries, losing out on the former after suffering a "bone explosion" in her wrist in a terrible fall at a meet.
The perils of this event were evident in the heats when Trinidadian Deborah John crashed into the fifth obstacle requiring medical attention for over 10 minutes before being fitted with a neck brace and stretchered off the track.
Pearson looked in determined mood right from the outset, dominating her heat to take it in 12.71sec from America's 2008 Olympic champion Dawn Harper-Nelson.
Pearson will reappear later on Friday for the semi-finals where she will face stiffer opposition and be able to measure herself against American world record holder Kendra Harrison.
Harrison looked good in her heat as she flew from the blocks and was never challenged, crossing the line in 12.60sec with Belarus 2015 world bronze medallist Alina Talay edging Jamaica's former world youth champion Yanique Thompson for second.
Defending champion Danielle Williams looked silky smooth in her heat, the Jamaican gliding over the hurdles to win in 12.66sec ahead of promising German champion Pamela Dutkiewicz.
Jamaica -- who have had a below-par championships -- look to have a strong hand in the event and their national champion Megan Simmonds impressed in leading from the gun to ease home in 12.78sec ahead of America's Olympic silver medallist Nia Ali.