ByMary Whitfill Roeloffs,

Forbes Staff.

The world’s top tennis players are battling it out on the court in the first round of singles competitions at the U.S. open, with some sporting high-dollar luxury watches and custom diamond jewelry worth tens of thousands of dollars.

Women’s No. 8 Amanda Anisimova has partnered with Tiffany & Co. for the U.S. Open and played her singles match Wednesday wearing several pieces from the brand’s Hardware Collection in gold, including two bracelets, earrings and a pendant necklace worth more than $10,000 in total.

Men's No. 3 player Alexander Zverev switched watch sponsors from Richard Mille to Jacob & Co. this year and sported a black watch in his Tuesday match (it’s still unclear exactly which model he was wearing at the Open, but it looked to be part of the brand’s Epic X line, which retail for between $24,000 and $140,000).