NEW YORK, Sept 3 (Reuters) - Here are five things to watch for on day eight of the U.S. Open on Monday.
* Labor Day Monday will mark the first Military Appreciation Day at Flushing Meadows, including discounted tickets for the military and appearances by high-ranking officers.
* Unseeded American Jennifer Brady will face the toughest test of her unexpected run when she kicks off the day against top-seeded Czech Karolina Pliskova in the fourth round.
* Also in the last 16, world number one Rafael Nadal faces Ukrainian Alexandr Dolgopolov, who attracted the attention of the Tennis Integrity Unit when he lost a match to a lower ranked opponent last month amid strange betting patterns.
* Third seed Roger Federer continues his bid for a 20th grand slam title when the Swiss takes on German 33rd seed Philipp Kohlschreiber in the fourth round.
* It could be another late night for American Madison Keys in the evening’s final match on Arthur Ashe Stadium against Ukrainian Elina Svitolina. Her third round match ended at 1:46 a.m. local time, just shy of the record of 2:26 a.m. (Reporting by Rory Carroll; editing by Ken Ferris)