New York - Tyson Gay, with the fastest 100 meters in the world this year, and Sanya Richards-Ross, running for the first time since the London Olympics, top the line-up for Saturday's Diamond League meet in New York.
Gay, the 100 and 200 world champion from 2007 who is pondering adding the 200 for this year's worlds in Moscow, won the Jamaica Invitational earlier this month in a world season-best 9.86 seconds and hopes for similar speed Saturday.
"I'm looking forward to running great," Gay said.
Two-time Olympic 4x100 relay champion Nesta Carter, second at the Kingston race in 10.03, will test Gay again alongside 2008 Olympic 100 runner-up Richard Thompson of Trinidad and Tobago and US 2012 4x100 relay Olympian Ryan Bailey.
Reigning Olympic 400 champion Richards-Ross, who underwent right big toe surgery after the London Games, has undergone a lengthy rehabilitation to make sure she is prepared for the run to the world championships.
Richards-Ross had been nagged by toe pain for two years before having surgery eight months ago, her recovery delayed by scar tissue.
"I'm feeling better. That's why I'm here," Richards-Ross said. "I might as well race the best and hope to pull a good time."
The New York field features last year's five top 400 women, including the past three world champions - 2007 world and 2008 Olympic champion Christine Ohuruogu of Britain, 2009 world champ Richards-Ross and reigning world champion Amantle Montsho of Botswana, who has this year's world-best time of 49.88.
Add Jamaicans Novlene Williams-Mills and Sherika Williams and American Francena McCorory and Richards-Ross will have an early idea of the challenge she might face in Moscow.
"Right into the fire," she said. "Just the way I like it."
Jamaica's Veronica Campbell-Brown, a two-time Olympic champion and reigning 200 world champion, will be tested by American Bianca Knight, who helped the US 4x100 relay team take Olympic gold, as she bids for a 100-200 world double.
Reigning world 100 champion Carmelita Jeter goes up against US compatriot Tianna Madison and Trinidad and Tobago's Kelly-Ann Baptiste, third at the 2011 worlds.
Reigning Olympic champion and world record-holder David Rudisha of Kenya highlights the 800 while two-time world champion and 2008 Olympic winner Jeremy Wariner faces Belgian Kevin Borlee and fellow American Tony McQuay in the 400.
Reigning Olympic women's pole vault champion Jenn Suhr, who set a world indoor record earlir this year, will be tested by London Olympic runner-up Yarisley Silva of Cuba and reigning world champion Fabiana Murer of Brazil.
Two-time Olympic shot put champion Tomasz Majewski of Poland will be tested by the US trio of former world champions Christian Cantwell and Reese Hoffa and Ryan Whiting, the reigning world indoor champion who has the year's world-best of 22.28m.
Other reigning Olympic champions in the meet include American triple jumper Christian Taylor and US women's long jumper Brittney Reese.