So, which one will it be: the American who is World champion, or the American champion?

Michelle Perry defends the title she won in Helsinki two years ago, but comes to Osaka not as the US champion, after Ginnie Powell beat her at the American trials.

That was Perry’s first defeat since July 2006, but it is hardly a harbinger of decline in the 28-year-old Californian who has a best this season of 12.44sec - within 0.01sec of her PB.

Perry and Powell are exceedingly well-matched: both are coached by Bob Kersee, and 23-year-old Powell’s PB is 12.45sec, set this season.

When the two women meet there are usually fireworks, as happened at the Paris Golden League, when Powell fell after clashing against her training partner mid-race.

Other likely contenders in this event include Susanna Kallur, Sweden’s European champion (12.62 best this season), Lolo Jones, the third-placer at the US trials (12.57 in 2007) and the recently crowned Pan-Am Games champion Delloreen Ennis-London (JAM).

Osaka 2007 News Team/sd