NEW YORK — No. 4 Novak Djokovic has ended American qualifier Jesse Witten's stay at the U.S. Open with a 6-7 (2), 6-3, 7-6 (2) 6-4 victory in the third round at Flushing Meadows.

Witten, ranked 276th in the world, checked into his New York hotel last weekend with five of his friends from University of Kentucky, figuring it would be a short stay. Instead, he won twice, and put a big scare into Djokovic on Saturday, as well.

Djokovic, the 2008 Australian Open champion, had his serve broken six times, but broke Witten nine times during the match that lasted nearly 3½ hours in Armstrong Stadium.

His victory kept the top 16 men perfect this week at the Open. The top 16 have combined to win all 35 matches they've played.