At his White House news conference yesterday, the president faced a string of questions about Iraq.

NPR: Bush Challenges Eavesdropping Detractors

In the question-and-answer session which followed, he faced a string of hostile questions about his stance on the strike by 300, 000 teachers and civil servants in June.

BBC: Ed Miliband heckled at TUC over pension strike stance

Now this string of withdrawals has again raised questions about Nadal's future: Can a man who plays with such intensity on chronically achy knees continue as a top player into his late 20s?

WSJ: Rafael Nadal Will Miss U.S. Open