MOSCOW (REUTERS) - Usain Bolt starts his quest for a second world track gold in Moscow but American sprinting great Allyson Felix looks set to steal the limelight as she goes for a fourth world 200m title on Friday.
Briton Mo Farah should also rubber-stamp his status as one of the all-time distance running greats - and repeat his Olympic feat from London - by adding a 5,000m gold to the 10,000 title he won on the first day of the championships.
The graceful-striding Felix won three Olympic golds in London last year at 200 and in the 4x100- and 4x400-metre relays, and is firmly on course to become the athlete to win most individual world championship golds.
Felix, Carl Lewis and Michael Johnson have all won eight.
The 27-year-old has most to fear from Jamaican Shelly-Ann Fraser-Pryce, whose 100m victory on Monday was probably the most impressive of the championships.
Compatriot Bolt, his 100m title safely reclaimed on Sunday, returns to the Luzhniki Stadium for the first round heats and semi-finals of the 200, the distance he prefers.
Defending world and Olympic 100m hurdles champion Sally Pearson gets her first feel of the Luzhniki track in the opening heats after "patiently waiting" until day seven of the championships.
"Staying focused on the job can be quite tough when you're at the end of the programme. You have to remain calm and relaxed," the Australian wrote in her blog.
Pearson has slowly regained form after an injury-hit season but faces a formidable challenge from the Americans, especially young sensation Brianna Rollins who ran the fastest time in 21 years when she clocked 12.26 seconds to win the United States trials in June.
Rollins' preparations have not gone without a hitch, however, the 21-year-old tweeting she had "banged my knee in practice" at the weekend.
While Rollins has plenty of time ahead of her to shine, compatriot and "golden oldie" Dwight Phillips bids to go out in a blaze of glory and secure a fifth world long jump title.
The 35-year-old delayed his retirement after missing last year's Olympics through injury.
Gold medals are also up for grabs in the women's hammer, men's shot put and men's 4x400m relay.