NEW YORK Aug 31 (Reuters) - Spain's David Ferrer became the first man to reach the round of 16 at this year's U.S. Open when he defeated Kazakhstan qualifier Mikhail Kukushkin on Saturday.
Ferrer, seeded fourth after reaching the French Open final in June, dropped a set for the second match in a row but was otherwise untroubled in his 6-4 6-3 4-6 6-4 victory.
Kukushkin matched his best performance at a grand slam by reaching the third round but contributed to his own downfall by committing 66 unforced errors, almost twice as many as Ferrer.
The Spaniard was a semi-finalist at the U.S. Open in 2007 and again last year. His next opponent will be either Janko Tipsarevic or Jack Sock. (Reporting by Julian Linden; Editing by gene Cherry)