Plagued by injuries and having lost some of her desire to compete, Clijsters initially retired from tennis in 2007 at the age of 23 to get married and have a daughter. She returned to the sport two years later and won her second US Open title as an unranked player in just her third tournament back. She defended her title the following year and then won the Australian Open in 2011 en route to becoming the first mother to be ranked No. 1 by the WTA. Along with Margaret Court, she also holds the record for most Grand Slam singles titles won as a mother, with three such titles, and was the first to win one since Evonne Goolagong Cawley in 1980. Clijsters retired again following the 2012 US Open. In 2020, after seven years of retirement from professional tennis, Clijsters began her second comeback at the Dubai Tennis Championships.