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UNITED STATES - SEPTEMBER 01: Memorabilia from the 1975 ?Battle of the Sexes? match between Bobby Riggs and Billie Jean King is on display at the U.S. Open in New York, U.S., on Aug. 31, 2009. The items are being auctioned on Sept. 13 with a presale estimate of $8,000 to $10,000. (Photo by Philip Boroff/Bloomberg via Getty Images)

UNITED STATES - SEPTEMBER 01:  Memorabilia from the 1975 ?Battle of the Sexes? match between Bobby Riggs and Billie Jean King is on display at the U.S. Open in New York, U.S., on Aug. 31, 2009. The items are being auctioned on Sept. 13 with a presale estimate of $8,000 to $10,000.  (Photo by Philip Boroff/Bloomberg via Getty Images)