Britain's Mara Yamauchi has set her sights on medals in this year's World Athletics Championships and in the 2012 Olympic Games after a spirited run to finish second in the Flora London Marathon.

Yamauchi lived up to her promise to carve "a big chunk" from her personal best for the distance by stopping the clock on 2hrs 23mins 11 secs, nearly two minutes faster than the Japan-based 35-year-old's previous mark.

It was not good enough to stop Irina Mikitenko, of Germany, successfully defending her London title.

But Yamauchi's gritty performance was just the boost British long-distance running needed in the injury-enforced absence of Paula Radcliffe.

Now she believes that, if Radcliffe is fit, Britain can double up on the podium in the world championships in Germany this August.

"Berlin will be a super-fast course, which is good for me," she said.

"Great Britain could win two medals in Berlin and that would be quite a result."

It would be even better in 2012. Yamauchi, sixth at the Beijing Games last August, said: "To run an Olympics in my own country would be very special. I hope I'll still be around.

"I've been improving for the past four or five years and if I can keep improving to 2hrs 20mins by 2012 then I believe I can challenge for a medal at the Games." Olympic champion Sammy Wanjiru, of Kenya, employed a series of surges to break the challenge of Ethiopia's Tsegay Kebede in the men's race. Wanjiru's time of 2hrs 5mins 10secs was a course record and more than 10 minutes faster than Andi Jones, who was Britain's first finisher in 13th place.

In the men's wheelchair race David Weir, of Britain, was denied a fifth victory around the streets of the capital by Australia's Kurt Fearnley.

American Amanda McGrory took the women's wheelchair event with former champion Shelly Woods, of Britain, having to settle for sixth.