Doha - The 17th edition of the IAAF World Athletics Championships gets under way on Friday, with a midnight marathon launching a 10-day battle for medals as the biennial event is staged in the Middle East for the first time.
A total of 1 972 athletes from 208 countries and territories will compete in the championships, which are seen as an important staging post as Qatar prepares for the challenge of hosting football's World Cup in 2022.
With the bulk of the competition taking place at the fully air-conditioned Khalifa Stadium, most athletes will be shielded from the ferocious heat and humidity in Doha, where temperatures can reach 40 degrees Celsius.
Marathon runners and endurance athletes, however, will be required to battle through the challenging climate alone, raising safety concerns.
The marathon and race-walking events have been scheduled for late at night to avoid the hottest part of the day, with Friday's women's marathon - where the first medals of the championships will be decided - starting under floodlights at 22:59 SA time.
International Association of Athletics Federations (IAAF) President Sebastian Coe said he is confident marathon runners will be able to cope with temperatures forecast at around 32 degrees Celsius and humidity of 80 percent.
Organisers however are leaving nothing to chance, with larger than usual teams of paramedics on hand and an abundance of water stations populating the course on Doha's Corniche waterfront.
"The overwhelming thrust of this is the welfare of the athletes," Coe said on Thursday.
"We will have more water on the course than we've ever had in any marathon, we will have more medical support and more paramedics out there as well."
While the women's marathon brings the curtain down on the first day of action, the newly renovated Khalifa Stadium will play host to the opening track and field events.
The highlights of the first day will include the opening heats of the men's 100 metres, where US sprinter Christian Coleman will aim to shrug off the missed drug-test controversy which threatened to derail his career.
Coleman, the fastest man in the world over 100m this season, faced being barred from the championships last month after it emerged he had registered three anti-doping "whereabouts failures" in a 12-month period.
However the charges against the 23-year-old American were withdrawn earlier this month because of a technical loophole.
Coleman is amongst a crop of young American sprinters hoping to fill the void created by the retirement of Jamaican sprint icon Usain Bolt, who hung up his spikes after the 2017 worlds in London.
The likeliest candidate to replace Bolt however could turn out to be Noah Lyles, the charismatic 22-year-old who is the favourite in the 200m, with the final taking place next Tuesday.
In the women's sprints, meanwhile, Jamaica's Shelly-Ann Fraser-Pryce is chasing a record fourth 100m gold at the age of 32, two years after skipping a season for the birth of her son in 2017.
Fraser-Pryce opens her 100m campaign in Saturday's heats with the final on Sunday.
Elsewhere during the championships, world records could come under threat in the men's and women's 400m hurdles.
Norway's Karsten Warholm is set for a battle royale in the men's event with American champion Rai Benjamin.
In the women's race, Olympic champion Dalilah Muhammad is hoping to improve her new world record of 52.20 set at the US trials in July.
There is no place in Doha though for South Africa's 800m star Caster Semenya.
The double Olympic champion misses out after losing a long-running battle against regulations requiring her to take medication to lower her naturally-elevated testosterone levels.
World athletics chief Coe, elected to a second term as IAAF president this week, hopes Doha will help draw a line under a turbulent first term dominated by the Russian doping scandal that erupted in late 2015.
"I can't actually remember a time in the sport when I've been so optimistic and excited about young talent coming through," Coe said on Thursday.
"The sport is in great shape."