Jamaican "Pocket Rocket" Shelly-Ann Fraser-Pryce is juggling being the fastest woman alive with motherhood as she bids for a third 100m Olympic gold－13 years after her first triumph.

The 34-year-old, who stands just 1.52 meters tall, is set for a mouthwatering clash in Tokyo with compatriot Elaine Thompson-Herah and Britain's 200m world champion Dina Asher-Smith.

US sprint star Sha'Carri Richardson was ruled out of the 100m in Japan after testing positive for marijuana at the US Olympic trials.

Fraser-Pryce won the first of her two Olympic 100m titles at the 2008 Beijing Games, becoming the first Jamaican to win the event after previous generations of sprinters including Merlene Ottey and Juliet Cuthbert came up short.

She won her first world championship title in 2009 before her career was disrupted by a six-month ban the following year after she tested positive for banned substance oxycodone, which she said was medication for a toothache.

Fraser-Pryce retained her 100m Olympic crown at London 2012, but failed in her hat-trick bid at Rio 2016, taking bronze behind Thompson-Herah.

She subsequently took time out to have a baby but returned in style to win a fourth 100m world title in 2019, also taking gold in the 4x100m relay, which was her ninth world championship gold.

The Jamaican veteran arrives in Tokyo in fine form after running a personal best of 10.63 seconds in "super spikes" in June to become the second-fastest woman of all time behind late US sprinter Florence Griffith Joyner, who timed 10.49 sec.

"10.6 has been a dream, a goal," she said. "I've been working so hard, been so patient and to see it finally unfold, I'm just ecstatic."

Tokyo will be Fraser-Pryce's first Olympics as a mother－she gave birth to her son Zyon in 2017－and says it has helped her put her life in perspective.

"It doesn't matter what happens on the field, my biggest accomplishment will always be my son and being able to come back to competition after having my son is also a big accomplishment," she told the BBC.

"And giving other female athletes hope of whatever it is you want to do in life, you do not allow anybody to dictate what you do and when you stop. You can keep going."

Fraser-Pryce grew up in a deprived area of Jamaica's capital Kingston that is plagued by gang violence, and has often spoken about how she did not always have enough to eat.

The sprinter has a degree in child and adolescent development and is passionate about improving children's lives.

AFP