|World Athletics Championships on the BBC|
|Venue:London Stadium Dates: 4-13 August|
|Coverage: Live across BBC One and Two, BBC Radio 5 live, BBC Radio 5 live sports extra and online|
Eight-time Olympic champion Usain Bolt ran his first sub-10-second time of the year to win the 100m at the Diamond League in Monaco.
The 30-year-old Jamaican clocked 9.95 in his final Diamond League race to beat America's Isiah Young (9.98) and South African Akani Simbine (10.02).
Britain's CJ Ujah ran 10.02 to claim fourth.
Elsewhere Britain's Laura Muir was comfortably beaten by Kenyan Hellen Obiri in the women's 3,000m.
With two weeks to go until the event, this was arguably Bolt's toughest test since he won double Olympic gold at Rio 2016.
The global icon laboured to victory in 10.06 in Ostrava last month but finally dipped under the 10-second mark against a much tougher field in Monaco on Friday.
In his final race before London 2017, which takes place from 4-13 August, Bolt showed signs he could well bow out with yet another gold medal.
Mike Costello, BBC athletics correspondent
It was workman-like for Usain Bolt but he edged in front over the last 40 metres.There were no real celebrations at the end but he wanted to run inside 10 seconds.
He said he gets it right when the championships come around.Now he has got two weeks to get it right in defence of his world title.
Muir outclassed in 3,000m
European indoor 1500m and 3,000m champion Muir was up against her fierce rival Obiri - the 2016 Olympic 5,000m silver medallist - in the 3,000m.
Scot Muir, who will contest both the 1500m and the 5,000m at next month's World Championships, was sent a clear message by the in-form Kenyan.
Obiri clocked an impressive eight minutes 23.14 seconds to secure a huge victory over compatriot Beatrice Chepkoech as Muir ran a personal best time of 8:30:64 but finished third.
Fellow Briton Eilish McColgan also ran a lifetime best as she put in a late change to take fourth in a time of 8:31:39.
The 21-year-old, who only returned to action last month, clocked a season's best time of 22.89 seconds to take third behind Marie-Josee Talou of the Ivory Coast (22.25) and American Kyra Jefferson (22.42).
Asher-Smith will run the women's 200m and the women's 4x100m relay at next month's World Championships.
Van Niekerk and Semenya impressWayde van Niekerk (right) broke the 300m world record earlier this year
The world's best flocked to a fast track in Monaco and were rewarded with a series of quick times in the final Diamond League event before August's World Championships.
South Africa's 400m world record holder and Olympic champion Wayde van Niekerk won the men's 400m in a meeting record of 43.73 seconds.
But he was pushed all the way by Botswana's Isaac Makwala, who ran another season's best time of 43.84 with countryman Baboloki Thebe in third.
In the women's 800m, South African Caster Semenya looked imperious in the final straight to power home in a national record and world-leading time of one minute 55:27 seconds, ahead of Burundi's Francine Niyonsaba.
Britain's Lynsey Sharp came sixth in a time of 1:58:01 - a season's best performance.
In the men's 800m, Emmanuel Korir continued his fine year with an easy victory in a world-leading time of 1:43:10 to send a message to fellow Kenyan David Rudisha.
British champion Eliot Giles struggled in the fast-paced race, coming home in ninth place in a time of 1:46:10....