Kim Clijsters will come out of retirement after a 7-year break, returning to the WTA Tour in 2020. 2 years after winning her first major at 2005 US Open, an injury-plagued Clijsters retired at the age of 23. But she returned two years later to claim her second US Open. She defended her title at Flushing Meadows next year and won Australia Open in 2011. Clijsters hung up her racket after the 2012 US Open.