Double 200m world champion Allyson Felix will be the bookies favourite when the competitors enter the blocks on the Olympic track in Beijing as the Los Angeles native aims to confirm her status as the top 200m runner in the world.

Narrowly beaten at the 2004 Games in Athens by Jamaica's Veronica Campbell, the American runner has since added the 200m world titles in 2005 and 2007 and is a key member of the relay teams where she has also picked up gold medals.

Her dominating run in Osaka in 2007 left 100m champion Campbell trailing in her wake but the Jamaican star still has that slight psychological edge having won their duel in Greece.

Felix also achieved the rare feat of winning golds in the 4x100m and 4x400m races in Japan which underlines her ability to maintain her speed over short or long sprints.

But with Beijing in view, Felix could only manage fifth place at the American Olympic trials and will miss the 100m, settling instead for a crack at gold in the 200m and relays.

Based on the sun kissed west coast of the United States, she was already showing signs of her talent as a young student winning California high school titles in 2002 over 100m and 200m.

Quickly spotted by the American sports media, her stock rose even further when she was featured in such respected publications as Sports Illustrated and USA Today before ever taking part at a major senior competition.

In 2003, she had risen to become the 8th ranked runner in the world over 200m and a step up the big time was just around the corner.

Although she settled for silver at her first Olympic Games in Athens, one year later in Helsinki she hit the top with the world title during a 2005 season in which she established her credentials as the woman to beat.

The 2006 season was transitional with no major meetings but in the pre-Olympic 2007 season, she defended her world crown in style easily beating Campbell in the searing Osaka heat.

Now the Beijing Games beckon and barring injury or disaster she will be hot favourite to win the ultimate prize when the gun goes to spark the women's 200m into life.

She attends the University of Southern California and her brother is a US junior 200m champion.

Away from the track, she likes to spend time with friends and watch a good film.