Serena Williams pulls out minutes before scheduled clash with Marion Bartoli . World No . 1 says back problem has troubled her for the past fortnight . Williams took to the court to apologize to fans who had arrived for her second-round match with Marion Bartoli of France . - Novak Djokovic wins his first title of 2011 in Madrid after beating Roger Federer to win 6-3, 7-6 (7-4) 6-4.
Serena Williams pulls out minutes before scheduled clash with Marion Bartoli . World No . 1 says back problem has troubled her for the past fortnight . - Novak Djokovic wins his first title of 2011 in Madrid after beating Roger Federer to win 6-3, 7-6 (7-4) 6-4.