THE HAGUE  -Dutch wheelchair tennis star Esther Vergeer announced her retirement on Tuesday after an astonishing unbroken run of 470 wins spanning more than 10 years. "A special day: officially stopping tennis," Vergeer, 31, wrote on the micro-blogging site Twitter, without elaborating on her reasons for retiring.Vergeer won four Paralympic tennis singles gold medals and three golds in doubles. Vergeer won her first gold medal in Sydney in 2000. She has been ranked number one in the world since 1999 and has not lost a singles match since January 2003.She has always insisted that she was not chasing the record of squash great Jahangir Khan, who tallied 555 consecutive wins between 1981 and 1986. "This is an amazing life still so why quit while I'm still winning?" she said last year. "But it's not like I'm aiming for the 500 unbeaten record, 600 or whatever." Vergeer was just a "little girl" when she started out in wheelchair tennis after losing the use of her legs aged eight following surgery, and she has grown up alongside the sport as it blossomed and gradually became more professional. "It's so amazing that I can spread the message to the world basically that if you have a disability there's so much that you can still do, and a lot of people in the world still don't know that," she said in Melbourne in January last year.After winning her last gold medal at the London Paralympics in 2012, Vergeer made clear that her winning streak was not accompanied by complacency. "Everybody expected me to win gold and that I would win but I still had to work hard, to go to training, to be at the top of my game. A lot of people forget that," she said.Vergeer's retirement comes after British wheelchair ace Peter Norfolk, dubbed "The Quadfather", announced last month that he was giving up full-time competition and would most likely not be at the next Paralympics in Rio de Janeiro in 2016. Norfolk, who won gold at the 2004 and 2008 Games in Athens and Beijing in the quads tournament for players with impairments to three or more limbs, carried Britain's flag at the London 2012 Games.