Four-time Grand Slam singles champion Clijsters' career ended Saturday, when she and Bob Bryan lost their second-round mixed doubles match at the U.S. Open to Ekaterina Makarova and Bruno Soares 6-2, 3-6, 12-10.
Clijsters and Bryan saved four match points in the super-tiebreaker before Clijsters netted a return on the fifth.
Clijsters, a 29-year-old Belgian, announced months ago the U.S. Open would be her last tournament. She lost to British teen Laura Robson in singles Wednesday, snapping Clijsters' 22-match winning streak at Flushing Meadows, where she won titles in 2005, 2009 and 2010.
Clijsters and Kirsten Flipkens lost to Chuang Chia-jung and Zhang Shuai in the first round of women's doubles Thursday.