Who will be the world's fastest woman in Doha?
The women's 100m final could be one of the most thrilling contests at the 2019 World Athletics Championships in Doha.
But Britain's Dina Asher-Smith is enjoying her best season yet, and is a genuine threat to the two Jamaicans.
Add African Games champion Marie-Josee Ta Lou, two-time reigning world 200m champion Dafne Schippers and three members of USA's victorious 4x100m relay team at Rio 2016, and you have one seriously competitive race.
Defending her world title is Tori Bowie who has had what might be described as an interesting season so far.
In January, she was kicked out of her training centre in California over an alleged unpaid debt.
Bowie won three medals at Rio 2016 - silver in the 100m, bronze in the 200m and gold in the 4x100m relay - before claiming individual and sprint relay gold at the 2017 London World Championships.
But Bowie did not compete on the track this year until June, focusing on trying to qualify for Doha in the long jump.
She very nearly succeeded, but finished in fourth at July's US trials in Iowa on countback having jumped 6.78m - the same distance as third-placed Sha'Keela Saunders.
That was enough to qualify her for the Worlds with defending champion and London 2012 gold medallist Brittney Reese already guaranteed a berth.
The 29-year-old has now switched back largely to the 100m, but she will have to improve markedly on her best time of 11.09s this season to be in with a chance of a medal.
The returning champ
Shelly-Ann Fraser-Pryce is the most successful female sprinter in history with two Olympic titles and seven world crowns including three (2009, 2013, 2015) in the individual 100m.
The 32-year-old missed the last World Championships, giving birth to her first child the day after Bowie took gold.
She returned to the track last season and clocked her best time since 2013 in June's Jamaican Championships.
It was not quite enough for victory, however, as Elaine Thompson edged her out with both women crossing the line in 10.73s, the fastest in the world this year.
That was a rare defeat in what has been a solid season with the diminutive 'Pocket Rocket' recording three of the five best times in 2019 and winning the Pan American Games 200m title in Lima.
The only non-Jamaican to break 10.80s this season, American teenager Sha'Carri Richardson, will not be in Doha after failing to make the frame in the US Championships.
While she has three Olympic golds to her name, Fraser-Pryce says she has drawn on her experience of taking bronze in the Rio 2016 100m as inspiration this year.
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A long-standing toe injury affected her preparations for the defence of her Olympic crown and, speaking to Nuffin' Long Athletics, she said, "To be able to overcome (the injury) the way I did kind of helps for this season.
"Sometimes in life you don't know what each season is teaching you, but you have to be mentally prepared to go through the season no matter what.
"I think 2016 was that year that mentally tested me. Even in training there were so many moments I cried, I was angry, I was upset, I didn't know what to do. But I was able to put it all together and still come away with a bronze medal." - Shelly-Ann Fraser-Pryce
Ahead of August's Birmingham Diamond League, Fraser-Pryce admitted her two-year-old son suffers "separation anxiety" when she leaves to compete:
"He was crying and he was holding onto the suitcase but it's part of the job. It's hard for me as a mum to actually leave him but it's something that I have to do and it's a sacrifice that you just have to get used to as an athlete."
In Doha, she will bid to become the first female track athlete to win four world titles in a single event.
The Rio sprint queen
At Rio 2016, Elaine Thompson became the first woman since Florence Griffith-Joyner to complete the Olympic sprint double.
A member of Jamaica's winning 4x100m relay team at the 2015 World Championships, the 27-year-old is still seeking her first individual world title having been fifth in the 2017 100m.
The 27-year-old has suffered just one defeat over 100m in 2019, finishing third in her first Diamond League appearance in Shanghai behind American Aleia Hobbs and Blessing Okagbare of Nigeria.
She is unbeaten in the short sprint since, but she and Fraser-Pryce have avoided each other since their tight finish at the Jamaican Championships.
Her times have not been as impressive as her compatriot, but Thompson says she's been making sure she peaks for Doha.
Speaking after her Paris Diamond League 100m win in late August, she said, "I'm feeling great and I'm getting in shape step by step, day by day.
"I'm not at 100 percent yet because it's all about the World Championships." Elaine Thompson speaking on 24 August
The British challenger
Dina Asher-Smith burst onto the scene as a teenager, taking fifth in the 200m at the 2015 World Championships a year after becoming world junior 100m champion.
She was also fifth in the 200m at Rio 2016 behind Thompson and fourth in the 2017 Worlds behind Dafne Schippers on home soil.
But the last 18 months have seen Asher-Smith establish herself as a genuine contender in both sprints.
While her strongest event is probably still the 200m, the Londoner did the double at the 2018 European Championships in Berlin as well as anchoring Britain to gold in the 4x100m relay.
And earlier this month, she defeated Fraser-Pryce in Brussels to take the 100m Diamond League title.
A week before that, the Briton was second to Shaunae Miller-Uibo in the 200m Diamond League Final in Zurich with Thompson and Dafne Schippers way back in third and fourth.
The Bahamian is only running the 400m in Doha, making Asher-Smith a warm favourite for the half-lap event.
But the 23-year-old told Telegraph Sport this month, "Wherever you are ranked you have to have confidence in your ability and your race plan.
"I’ve done more 200s internationally since I was younger, so technically I’m probably less experienced than some of the ladies are internationally [over 100m], but that doesn’t mean anything when you come to a championships.
"I’m confident of both because that’s the mentality you have to have." Dina Asher-Smith speaking to Telegraph Sport
Ta Lou and Schippers head threats
After taking silver in both the 100m and 200m two years ago in London, Marie-Josee Ta Lou is hoping to claim her first global title.
The Ivorian sprinter won the 100m at the Prefontaine Classic with Fraser-Pryce down in eighth after suffering some "slight knee pain".
But Ta Lou was well behind Asher-Smith and Fraser-Pryce in Brussels and will need to return to something like her best to challenge the big three.
Compatriot Murielle Ahoure, the 2018 Diamond League 100m champion, has made few appearances this year.
Ahoure's African record of 10.78s set in June 2016 would put her right in the mix but a season's best of 11.15s does not mark out the 2013 dual silver medallist as a contender.
On her best form, two-time 200m world champion Dafne Schippers would be right in the mix.
And while her times this season are nothing to write home about, the Dutchwoman insists she will be in top shape for the big occasion.
Speaking at a press event in Papendal, she said, "I am a championship runner. I know what to do at championships. If I reach the final, we'll see what happens.
"You have to be able to fight at a championships. I can do that." - Dafne Schippers as reported by Trouw.nl
An intermittent back problem caused by falling down the stairs in February has affected her starts, but she expects to be fully fit when she lines up in Doha.
The American challenge looks weaker than in previous year with Teahna Daniels winning the trials having set a personal best of 10.99s in May.
Runner-up to Daniels in Des Moines was English Gardner whose season's best is more than four-tenths down on her personal best of 10.74s achieved in the trials for Rio 2016.
Gardner was seventh in the Olympic final and handed over to Bowie as the USA took gold in the 4x100m relay from Lane 1.
Morolake Akinosun was third in the US Championships.
She is another Olympic gold medallist having run the anchor leg for the 4x100m team in a special solo run-off in Rio after Allyson Felix was bumped by a Brazilian runner in the heats.
But a season's best of 11.20s means Akinosun has leaves her work to do to make the final.