Venus Williams has joined her younger sister, Serena, in withdrawing from the French Open due to injury, her agent confirmed on Saturday. The 30-year-old seven-time Grand Slam champion has not played since January, when she pulled out of the Australian Open in the third round with an abdominal injury. A knee problem meant Venus played just one tournament in the last half of 2010 but she still finished the year inside the top five in the world rankings. Now number 19 in the world, Venus has not won a Grand Slam singles title since 2008, when she won Wimbledon for the fifth time. Serena withdrew from Roland Garros on Thursday, having been out of action since last summer due to two foot operations and the discovery of blood clots in her lung. Venus\'s withdrawal means this year\'s French Open, which begins on May 22, will be the first Grand Slam tournament without either Williams sibling since the 2003 US Open.