NEW YORK, Sept 6 (Reuters) - Here are five things to watch for on day ten of the U.S. Open on Wednesday.
* Humidity is expected to give way to thunderstorms at Flushing Meadows but play will continue uninterrupted under the $100 million retractable roof at Arthur Ashe Stadium.
* World number one Karolina Pliskova will look to build off the 46-minute straight sets win that earned her a place in the quarter-finals when she battles hard-hitting American CoCo Vandeweghe to kick off the morning action on Ashe.
* World number one Rafael Nadal will meet fresh faced 19-year-old Andrey Rublev of Russia for the first time as the veteran Spaniard tries to set up a possible semi-final battle against rival Roger Federer.
* Fifteenth-seeded American Madison Keys can expect strong backing from the partisan New York crowd when she faces unseeded veteran Estonian Kaia Kanepi in the first night match on Ashe.
* Third-seed Federer will battle 24th-seeded Argentinian Juan Martin del Potro in a rematch of the 2009 U.S. Open final to wrap up the action on Ashe. (Reporting by Rory Carroll; Editing by Toby Davis)