Yamauchi forced out by foot injury

And then there were three. Britain's medal prospects two months out from the world championships in Berlin have not exactly been looking the brightest, what with only four athletes ranked in the world's top 10 this year in events that will be contested in the German capital in August.

They were looking even dimmer yesterday with the news that one of the quartet will be missing because of injury.

Ranked second in the marathon after her 2hr 23min 12sec time as runner-up to Germany's Irina Mikitenko in London in April, Mara Yamauchi has withdrawn from the British team because of a foot problem. "After thinking it over very carefully, unfortunately I have come to the conclusion that I will not be able to race competitively in Berlin," she said. "There is insufficient time left to enable me to prepare properly for such a high quality race and reach the start line in 100 per cent top shape."

It is a major blow both for Yamauchi and for Britain. Sixth in the Olympic marathon in Beijing, the Tokyo-based Oxford woman showed with her London run that she has broken into the elite global class. She would have been a strongly fancied medal contender in Berlin.

It remains to be seen whether Paula Radcliffe, who missed the London Marathon because of a foot problem, will be able to get herself in sufficient shape to mount a medal challenge in August. As it is, only three British athletes other than Yamauchi stand in the world's top 10 this year: Jessica Ennis (first in the heptathlon), Phillips Idowu (fifth in the triple jump) and Dai Greene (seventh in the 400m hurdles).

Yamauchi's withdrawal followed news that UK Athletics are to focus their attention on just two performance centres in the run-up to the 2012 Olympics. The Lee Valley Athletics Centre in north London and Loughborough University have been selected by the governing body's Olympic Taskforce to become designated 2012 Performance Centres. This means a down-grading of the existing UKA High Performance Centres in Birmingham and West London (a split site between Brunel University and St Mary's College) to the status of regional training centres.

Charles van Commenee, head coach of UK Athletics, said: "Lee Valley and Loughborough are already good centres for performance sport but 'good' is not good enough. If we want to win Olympic and World Championship medals, we need 'excellence'. We will make these centres world-leading environments of excellence."