For only the second time this year, Novak Djokovic (left) tasted defeat. (JOHN SOMMERS II/REUTERS)

In Sunday’s Western & Southern Open final against Andy Murray, it was the latter that befell Djokovic.

A sore right shoulder — possibly the result of all the whoopings he’s delivered to the rest of the tour this summer — forced Djokovic to retire in the second set of Murray’s 6-4, 3-0 victory.

Djokovic (57-2 in 2011) had won 16 straight matches since his French Open semifinal defeat to Roger Federer, but Sunday’s loss revealed the physical toll maintaining such a high level of play can take on the player. More importantly, the injury provides hope to all the players looking up at Djokovic in the ATP rankings as they gear up for the U.S. Open at the end of the month.

Sunday night on his Twitter feed, Djokovic apologized to fans — in a bi-lingual pair of tweets — and assured the public that the injury should not keep him out of the U.S. Open.

“Dear friends and fans,i want to apologise to all of you who expected a better and longer match today. Shoulder could not take it anymore,and it didn't make sense to continue. Congratulation to Andy Murray for successful week. Thank you very much for the support,and see you in NYC.I will work on the recovery of my shoulder in next 7,8 days,and i hope and believe that everything is going to be ready for Us Open.”

If the Djoker can’t get back to 100 percent before he arrives in Flushing Meadows, it may provide a little extra pep to the step of Rafael Nadal and Roger Federer. Both suffered surprising quarterfinal exits in Cincinnati — Nadal’s coming one day after a 3-hour, 38-minute match followed by doubles — and neither has won a tournament since Nadal took a record sixth French Open back in early June.

Next month’s tournament may also provide the best opportunity in several years for an American male to win the Open since Andy Roddick did it in 2003. Mardy Fish is at the top of his game — having advanced to four consecutive semifinals — and is currently ranked No. 8 in the world.

On the women’s side, a rash of injuries will continue to promote parity in a season in which predicting a Grand Slam winner has been about as reliable as a game of Russian roulette.

Two-time defending U.S. Open champion Kim Clijsters withdrew from the tournament last week as she continues to deal with a strained abdominal muscle. Her departure further opens a draw featuring former champions Serena Williams and Maria Sharapova, who have overcome injuries of their own this season.

A sore toe forced Williams out of the Western & Southern Open last week, but the three-time U.S. Open champion expects to be fully healed before the final Grand Slam of the year begins. The troublesome toe wasn’t enough to keep Serena off the dance floor at Kim Kardashian’s wedding, however.

Sharapova, meanwhile, appears in good form after taking the Western & Southern Open title with a three-set victory over Jelena Jankovic. If you’re looking for a an early tournament favorite, she may be your best bet. Or you could throw a dart at the bracket and just go with whoever you hit. Either way.