The 17th edition of the IAAF World Athletics Championships kicks off on Friday in Qatar – the first Middle Eastern country to host the biennial competition.
More than 1,900 athletes from 210 countries will take part in 24 events over 10 days.
And the pressure is on organisers to keep everyone cool.
Most events will be held at a stadium with air cooling technology. But some athletes will have to compete also against high temperatures and humidity.