Osaka, Sept. 2 - Zhou Chunxiu became China's first marathon medalist in major world championships after winning the silver here on Sunday.Zhou, a surprise winner in this year's London Marathon, led with two kilometers away but 2003 world champion Catherine Ndereba overtook her and won her second world title in 2:30:37.But a second place finish was enough to make history. Zhou was the first Chinese to win a medal at Olympic or world championships marathons.Zhou, this year's fastest marathoner with 2:20:38, clocked 2:30:50 in Osaka's sweltering heat. Japan's Reiko Tosa won the bronze in 2:30:55.Zhou has been regarded a favorite since surprising a strong field to win the London marathon last April. The 28-year-old was fifth in the last worlds and was a distant 33rd in the Athens Olympics.The race started at 7 a.m. local time to avoid the heat that has bothered athletes at the championships. The temperatures reached 31 celsius degrees with humidity at 52 percent as the leaders approached the finish.Zhou complained about an ankle injury and the weather after the race."At the end, the last two km, my foot started to hurt. One week before coming to the championships I got hurt in China at the inner side of my right ankle. I got treatment and it got better. But this is one of the reasons why at the end I could not stick to Catherine Ndereba," she said."The other reason is the weather here. Catherine was very strong today. It feels just O.K. to have the silver medal."But she is confident that she can do better at next year's Beijing Olympic Games."Now, I will go back to China, have a rest. This was my last big competition for this year. In 2008, at the Olympic Games, everything will work in favor of me, because it is my home country."Zhou's silver is China's third medal in the world championships. Liu Xiang won a gold in the men's 110m hurdles and Zhang Wenxiu took a bronze in the women's hammer throw.