Former champion Lleyton Hewitt has outclassed Russian Evgeny Donskoy to reach the last 16 of the the US Open for the first time since 2006.

Hewitt backed up his vintage five-set win over sixth-seeded 2009 winner Juan Martin del Potro with a 6-3 7-6 (7-5) 3-6 6-1 victory over Donskoy at Flushing Meadows on Sunday.

Twelve years after winning the title in New York, Hewitt next meets either German 12th seed Tommy Haas or Russian 23rd seed Mikhail Youzhny on Tuesday for a likely quarter-final crack at world No.1 Novak Djokovic.

Hewitt played within himself but was still much too classy for the 102nd-ranked Donskoy, who was bidding to make the fourth round at a major for the first time.

After confidently winning the opening set, Hewitt snatched the second in a tiebreaker, hit a flat spot in the third before powering through the fourth with two more service breaks to comfortably advance.