World champion Amantle Montsho takes the 400m in the Stade de France (Jean-Pierre Durand) © Copyright

Women's 400 Metres - PREVIEW

When the gun sounds the opening round of the women’s 400m on 3 August, the focus of the event will firmly fall on three women: reigning World champion Amantle Montsho, 2009 World champion Sanya Richards-Ross, and Briton Christine Ohuruogu, the defending Olympic champion.

With just one loss in five competitions over the distance and two of the year's four fastest performances, Richards-Ross seems to have prepared well for another Olympic podium finish; her hope is two steps better than the bronze she won in Beijing four years ago.

Since storming to the World indoor title in Istanbul in March, Richards-Ross, now 27, took strong victories in Ostrava and the Prefontaine Classic in Eugene - the latter in 49.39 - before taking the U.S. title in 49.28. Given her tough U.S. trials schedule of six races in eight days - she also finished third in the 200m and will double in London - she hasn't raced since.

Montsho has engaged in a slightly higher profile pre-Olympic campaign, bagging victories in Kawasaki, Oslo, and Paris, the latter on the heels of her successful African title defense in Porto Novo. Despite the lack of any serious challenge there, Montsho improved her own Botswana national record to 49.54 to rank fourth fastest in the world prior to London.

Ohuruogu meanwhile has had a much more modest build up with her only international win in five starts coming at the Diamond League stop in London where she clocked a season's best 50.42, her fastest since 2009. As the reigning Olympic champion, the pressure on the 28-year-old Briton will be immense. How well she'll shoulder that burden is one of the biggest questions looming over the entire London athletics programme.

Yet none of the trio will arrive in the British capital as the season's fastest - that honour rests with Antonina Krivoshapka who sped to a 49.16 victory at the Russian Championships. Even the runner-up in that race, Yulia Gushchina at 49.28, is tied with Richards-Ross as the year's second fastest.

Krivoshapka is a proven championships competitor, with the 2009 World bronze along with multiple World and European relay medals to her name. Her winning time at the nationals in Cheboksary took down her previous 49.29 PB set in 2009.

Gushchina has made her move up to a long sprinter complete this season with her first sub-50 performances. Both of those came in Cheboksary, but like Krivoshapka, is largely untested outside of Russia this year.

Russian No. 3 Tatyana Firova (49.72) and Jamaican Novlene Williams-Mills (49.78) have also dipped under 50 seconds in 2012 and cannot be discounted as podium threats. Francena McCorory, who was third at the U.S. trials and improved to 50.06 this year with her victory in New York, has the experience of a fourth place finish in Daegu under her belt. Veteran DeeDee Trotter, who was fifth in the 2004 Games and both the 2005 and 2007 World Championships, clocked 50.02 at the U.S. Trials, her quickest time since 2007.

Bob Ramsak for the IAAF