World's top tennis player Novak Djokovic of Serbia won his first U.S. Open title Monday evening after beating defending champion Rafael Nadal of Spain 6-2, 6-4, 6-7, 6-1 in the men's final at Flushing Meadows in New York.

Djokovic, who produced a masterful display of tactics and precision in windy conditions at Arthur Ashe Stadium, took four sets and more than four hours to beat the same man who beat him in last year's final.

For Nadal, it was the sixth loss to the Serbian this year, all in finals, including at Wimbledon.

The match was originally scheduled for Sunday but was delayed due to heavy rain last week.

Meanwhile, American tennis player Serena Williams has escaped with a $2,000 fine for her angry rant during Sunday's U.S. Open women's final match against Australian Samantha Stosur.

U.S. Tennis Association tournament director Brian Earley ruled Monday that Williams' verbal abuse of the Greek chair umpire Eva Asderaki, who oversaw her shocking loss to Stosur, was not a “major offense.” Earley said the fine was consistent with similar offenses at Grand Slam events.

Stosur had defeated tournament-favorite Williams in straight sets, pulling off one of the biggest upsets in U.S. Open history. The ninth-seeded Stosur needed just 73 minutes to beat Williams 6-2 6-3, becoming Australia's first woman to win a Grand Slam title in more than 30 years.

Williams, who was on the last day of a two-year probation over a similar incident during a semi-final match with Kim Clijsters at the 2009 U.S. Open, could have faced a more severe penalty. Two years ago, Williams was handed a fine of $82,500 and a suspension for the expletive-laden verbal abuse of a lineswoman.

Williams unleashed her latest tantrum after being penalized for shouting “Come on!” after hitting what she thought was a game-winning shot. The umpire determined that Williams had committed “verbal hindrance,” intentionally interfering with Stosur's game. Williams proceeded to shout at the umpire, calling her a “hater” and “unattractive inside.”