Doha - Caster Semenya breezed to victory on Friday in the women's 800m at the Doha Diamond League meeting, clocking a world best time for 2016 of 1:58.26, just three months before the Olympics.
Semenya powered through the final 200m to head a world-class field and confirm her return to her very best form.
In doubly bad news for her rivals in an Olympics year, the South African admitted afterwards that she had held back from running at full pace during the race.
"I am just quite happy with anything under two minutes," she said.
"We are just focused on the time. I had to hold back a bit as it wasn't my pace. It's all about running well in every race."
Friday night's time at the Qatar Sports Club stadium would have been good enough for her to finish sixth at the 2012 London Olympics.
She seemed to labour through the first 500m and was well down the field as they approached the final bend.
But then she eased past her rivals to secure first place.
Ethiopia's Habitam Alemu came second in a personal best time of 1:59.14 and Eunice Jepkoech Sum was third in 1:59.74, a season's best for the Kenyan.
Asked how she was achieving such good times so early on in the season, Semenya said: "I think it is just hard work, hard work, plus I have been patient for almost three years."
Semenya says she has had knee problems over that time.
The 25-year-old's impressive victory came after an astonishing performance last month back home winning three races -- the 400m, 800m and 1 500m - in one afternoon.
There she ran the 800m in 1:58.45.
Semenya has been dogged by controversy since bursting onto the scene in the 2009 World Championships.
Following that victory she was subject to a gender test before going on to secure silver medals at the 2011 World Championships and 2012 Olympics.
Her early season form suggests she could become one of the major talking points in an Olympics year, with some already suggesting her resurgence may be due to a decision last year by CAS to suspend testing on female athletes taking testosterone suppressants.
It has not known, however, if Semenya has even ever been on such medication.
On Friday, she also seemed to dismiss running the 400m at the Olympics, even though ran that distance in a time of 50:78, another personal best.
"It's all about the 800m, the 400m is all about playing around with my speed," she said.
Elsewhere, it was Kenyan middle-distance runners who impressed.
the men's 1 500m, three-time world champion Asbel Kiprop destroyed a
high-class field to underline his stated intention to reclaim Olympic
gold later this year.
The Kenyan cruised home by a margin of
around 10m and even had time to wave to the crowd as he made his way
down the final 50 metres.
Kiprop - also the 2008 1 500m Olympic
champion - won in a time of 3:32:15, more than a second-and-a-half
ahead of fellow countrymen Elijah Manangoi and third-placed Silas
The Kenyan 1-2-3 delighted thousands of East African fans among the crowd.
There was another Kenyan clean sweep in the men's 3 000m steeplechase.
Kipruto, world champion silver medallist in 2013 and 2015, won in a
time of 8:05.13, three seconds ahead of Jairus Kipchoge Birech and
In total, eight Kenyans finished in the top 10 in the steeplechase.
Kenya holds its Olympics trials between June 14 and 16.
It was also a good night for the USA.
In the men's 200m, American Ameer Webb won in a lifetime's best time of 19:85.
Compatriot Christian Taylor won the triple jump with a distance of 17.23m.
And American Tori Bowie beat Dafne Schippers and Veronica Campbell-Brown to win the women's 100m.
Omar McLeod won the 110m hurdles with Olympic champion Aries Merritt,
returning from a kidney transplant last September, running a season's
"I am fine with that, every time I run I am setting a season's best," said the American afterwards.