The following is a list of the women tennis players who have the highest lifetime winning percentages at the U.S. Open in singles play. The list is a fascinating one because the woman player with the highest lifetime winning percentage at the U.S. Open is also the woman who has played the most matches in U.S. Open history.
Also, an active player on this list can become the top player on the list if she wins the U.S. Open in 2014. I'm only including Open Era stats here, and a player must have played in at least 50 U.S. Open matches to qualify for the list.
Prior to the Open Era, Helen Willis (.962, record of 50-2), Molla Bjurstedt Mallory (.903, record of 65-7), and Margaret Court (.895, record of 51-6), all had winning percentages at the U.S. Open that would be at the top of this list. But those win percentages were compiled mainly against amateur players (Margaret Court played both before and after the Open Era began in 1968).
I've been a tennis fan for over 40 years now, and any records that were compiled against just amateur competition have to be looked at differently in my opinion. Stats are through the 2013 U.S. Open.
Women tennis players with all-time highest winning percentages at U.S. Open
1. Chris Evert - .894
Chris Evert played in the U.S. Open from 1971 to 1989, and had an overall winning percentage of .894. That is highly impressive considering that Chris Evert also played the most singles matches of any woman at the U.S. Open ever with 113.
Over 113 matches at the U.S. Open, Chris Evert's record was 101-12 (.894). Chris Evert won the U.S. Open tournament a record six times in singles play.
2. Steffi Graf - .890
With a lifetime win percentage of .890 at the U.S. Open, Steffi Graf is not far behind Chris Evert. Steffi Graf had an overall record of 73-9 at the U.S. Open. Excellent to be sure, but Steffi Graf only played in 14 U.S. Open tournaments compared to 19 for Chris Evert.
3. Serena Williams - .889
So far in her U.S. Open career (through 2013), Serena Williams has an overall record of 72-9 good for a win percentage of .889. If Serena Williams wins the U.S. Open in 2014, she will vault to the top of this list.
4. Monica Seles - .841
Monica Seles had a record of 53-10 at the U.S. Open from 1989 to 1992 and 1995 to 2002. She won the tournament twice in 1991 and 1992.
Monica Seles was never really the same after she was stabbed in Germany during a match vs. Steffi Graf in 1993. She had won nine Grand Slam events before the stabbing and then won just one more after the incident.
5. Venus Williams - .838
Through 2013, Venus Williams has an overall record of 62-12 at the U.S. Open, good for a winning percentage of .838. Venus has won the U.S. Open twice in her career (2000, 2001).