Double Olympic champion Daley Thompson believes heptathlete Jessica Ennis is already "good enough to beat the world" and warns her against over-training in preparation for London 2012.
Ennis failed to retain her world title in Daegu this summer, beaten to the gold medal by Russia's Tatyana Chernova, but Thompson believes she has a "great shot" at winning in London and should "believe" in her ability to do so.