Top-seeded Novak Djokovic advances into U.S. Open round of 16

Novak Djokovic is a mainstay in the late rounds of the U.S. Open, but the world's top-ranked player has never has a path as easy as this year.

Djokovic advanced to the Round of 16 for the 10 consecutive year when Russia's Mikhail Youzhny retired after just six games Friday in their third-round match at Flushing, N.Y.

The 31-minute victory sent the defending champion into a matchup against either American John Isner or Great Britain's Kyle Edmund.

The top-seeded Djokovic won his opening match in four sets before moving on with a walkover in the second round.

Djokovic won the first three games against Youzhny, who informed the umpire he was done after delivering a forehand winner to close out the sixth game.

Ninth-seeded Jo-Wilfried Tsonga of France also advanced to the fourth round by dispatching Kevin Anderson of South Africa in straight sets, 6-3, 6-4, 7-6 (4).

It is the fifth consecutive year Tsonga is in the Round of 16, setting up a match against American Jack Sock, who stunned No. 7 seed Marin Cilic with a 6-4, 6-3, 6-3 victory.

Sock converted four of six break points against the big-serving Cilic and needed only 1 hour, 41 minutes to complete the upset of the 2014 U.S. Open champion.

Also moving on was 10th-seeded Frenchman Gaels Monfils, who breezed to a 6-4, 6-2, 6-4 win over Nicolas Almagro of Spain.

Up next for Monfils is Cyprus' Marcos Baghdatis, who advanced to the fourth round at a major for the first time since 2009 by beating American Ryan Harrison, 6-3, 7-6 (4), 1-6, 6-1.