Gatlin, De Grasse ready for early athletics season
They finished second and third in last year's Olympics 100m final and on Friday Justin Gatlin and Andre De Grasse renew their rivalry in the Diamond League season-opener in Qatar.
The sprint race is not the only standout event of the now-traditional Doha curtain-raiser for the league -- this year spread over 14 meetings in 13 different countries -- but is given an extra edge coming as it does in a World Championship season.
Both athletes will have their eyes on London in August, when they will take on the legendary Usain Bolt in his international farewell, but for now battle commences in Doha.
Canadian De Grasse, 22, is Bolt's heir apparent and has already said that he wants to "spoil" the legendary's Jamaican's goodbye to athletics.
De Grasse also claimed silver to Bolt in the 200m in Rio.
The controversial Gatlin, 35, has already struck an early season blow, anchoring his American team to victory at the IAAF World Relays in Nassau last month, De Grasse's Canada bombing out in the final.
The pair will be joined in Doha by another former Jamaican 100m world record holder -- and last year's Diamond League winner -- the evergreen Asafa Powell and yet another rising star, Akani Simbine.
The South African, 23, ran 9.92sec in March, the second fastest time of the year so far.
His early season form has been superb, dipping under 10 seconds five times and winning his country's 100m title ahead of Wayde van Niekerk.
The women's 200m will be contested by the gold and silver medallists from Rio -- Jamaica's Elaine Thompson and Dafne Schippers from the Netherlands.
Last year's bronze medallist in Rio, Tori Bowie from the US, is not in Doha but has already made her presence felt by clocking the year's fastest time so far, 22.09sec.
In recent years in the Doha leg of the Diamond League, some of the best performances have come in the middle and long-distance races.
This year could prove the same.
All three female 800m finalists from Rio -- South Africa's Caster Semenya, Burundi's Francine Niyonsaba and Kenya's Margaret Wambui -- will race on Friday.
They will be joined by Ethiopia's Genzebe Dibaba, a former 1500m world-record holder who has chosen an extremely tough field in which to make her 800m debut.
In the 3000m steeplechase, Kenyan-born Bahraini runner Ruth Jebet, who won gold in Rio, will make her season debut.
She is also the current world record holder with a time of 8mins 52.78.
Off the track, there's another clash of Olympic gold and silver medallists from Rio, when Greece's Ekaterini Stefanidi takes on America's Sandi Morris in the pole vault.
Friday's meeting marks the beginning of the eighth season of the Diamond League.
As with many other athletics events, it comes at a time of controversy within the sport.
The build-up has been overshadowed by a controversial European Athletics' proposal, which could see all world records set before 2005 written off as the sport tries to set a clean slate in its fight against doping.