The World Championships start in Doha on Friday with the globe's best athletes travelling to Qatar.
Here, PA Sport looks at the international athletes to watch at the Khalifa International Stadium.
Shaunae Miller-Uibo
The 400m Olympic champion has not lost a race for two years and is expected to take the 400m crown in Doha.
She has been in imperious form and it would be a shock not to see the 25-year-old win.
In a huge boost to Dina Asher-Smith Miller-Uibo will not run in the 200m because the schedule is too tight.
Karsten Warholm
The charismatic Norwegian produced the second-fastest 400m hurdles performance of all time at the Diamond League final last month.
He ran 46.92 seconds to become the third man to crack the 47-second barrier.
Warholm will be seen as the favourite for the title even if Rai Benjamin and home hero Abderrahman Samba will challenge him for gold in Doha.
Christian Coleman
The favourite for the 100m comes into the championships under a cloud.
He has been cleared to run after the US Anti-Doping Agency withdrew its case after the 23-year-old was charged with missing three drugs tests and faced an automatic one-year ban.
Coleman, who came second behind Justin Gatlin in the 100m two years ago, has always denied the charge.
Shelly-Ann Fraser-Pryce
The Jamaican remains the biggest threat to Dina Asher-Smith in the 100m – even if the Briton did beat her in the Diamond League final.
She ran 10.73 seconds in June and is a double Olympic champion, having taken the 2008 and 2012 100m titles.
World championship victories in 2009, 2013 and 2015 underline her lasting quality and, at 32, she could become the oldest woman to win a world title.
Nafi Thiam
The defending heptathlon champion, who also holds the European and Olympic title, remains the one to beat.
Katarina Johnson-Thompson is pushing her close but Thiam remains ahead of all challengers so far.
The 25-year-old beat Johnson-Thompson by 57 points at the Europeans in Berlin last year and has been just out of reach.
