Djokovic headlines suffering stars

CINCINNATI -- The tennis circuit limped out of Cincinnati last week, with one player after another pulling up hurt in the last big event before the U.S. Open. The final exclamation mark came as top seed Novak Djokovic retired down 7-5, 3-0 to Andy Murray in the title match at the Western and Southern Open, just the second blemish of his amazing season run.

"Generally I was quite exhausted playing many matches, but the exhaustion is not the reason," said Djokovic, who is now 57-2 for the year. "The reason is shoulder pain. I just could not serve. I served an average 90 miles per hour the first serve, and I could not play forehands [stretched out wide]."

The Serb's body sagged after he lost the first set and he received treatment on his shoulder before the start of the second. Once notorious for quitting with various breathing and stamina ailments, it was his first retirement since last May, when he found himself struggling with allergies. "You know, I could have maybe played another couple of games, but what for? I cannot beat a player like Murray today with one stroke," he said.

Although he won the Rogers Cup in Montreal just more than a week ago, Djokovic had insisted he wasn't about to run out of energy but then looked tired and served poorly during most of his Cincy matches. "I mean, it's kind of expected," he finally said on Sunday. "I've played so many matches this year. I've been winning a lot and reaching the final stages of each event that I've participated on. You know, considering the schedule that is very busy in tennis, it's kind of normal to expect that at some stage you are exhausted."

A day earlier, Djokovic was the beneficiary of a retirement, when Tomas Berdych could no longer go also because of shoulder problems. Both men said they had not had MRIs to determine the exact source of the problem but anticipated being fit for the U.S. Open.

Last week, it was Jo-Wilfried Tsonga who gave up against Djokovic in the semifinals of Montreal, citing a muscle pull in his arm, which seemed to have also bothered him during his loss in Cincinnati.

Overall, 10 of the top 30 have missed an event or had to retire during the past few weeks with injury. The laundry list includes David Ferrer (returning in Cincinnati after a hand problem), Robin Soderling (due to return at the U.S. Open after a wrist injury), Andy Roddick (abdominal), Mardy Fish (heel), Jurgen Melzer (muscle pull), Milos Raonic (hip surgery) and Michael Llodra (rib and arm problems, though apparently not tennis-related). Some are less significant than others -- Llodra has won two doubles titles and reached the final of a third in the past three weeks -- but there are also others who have played through their problems, such as Rafael Nadal with burns on his fingers (again not tennis-related) and Gilles Simon (neck stiffness). With back-to-back Masters events the past two weeks, fatigue hit several players in Cincinnati, as well -- mostly obviously Nadal, Gael Monfils and Murray in the semifinals.

With five weeks off between playing required events at Wimbledon and Montreal, it was a little surprising to see three of the big four struggling -- only old man Roger Federer was ready to pronounce himself "physically perfect" going into the U.S. Open. In the case of Djokovic, he was the only one of the four to do well at both Montreal and Cincinnati, playing 10 matches in 12 days. For Nadal and Murray, lack of play seemed to be the problem. After a long break, both made quick exits in Montreal and then had to adjust to logging a lot of time on the court in Cincinnati.

What does it mean for the U.S. Open? Probably not much. "I'm sure come the start of the U.S. Open next Monday, all of them will be fine," said Murray of his Grand Slam rivals. "I think each one of them will be playing great tennis, much better than they have played here."

The one-week, best-of-three sets Masters events present different challenges from the two-week, best-of-five Grand Slams, he added. "I think you can't really have bad days in these tournaments," Murray said. "In a three-set match, if you come out flat, the match can get away from you really quickly. Also, you don't have a day to work on things like you do at the Slams. Here you have to play well throughout the five days in a row, so you can't have an off day.

"But I mean, physically the Slams are more challenging. Mentally, two weeks is a long time to be focused for. So Slams are definitely tougher."

Most seeded players are taking a week off to rest and recover, though a few who have to make up match play, like Roddick, are trying to fit in some last-minute preparation at the Winston Salem Open this week. But the rash of injuries has claimed a few. Sam Querrey (elbow surgery) and Tommy Robredo have announced they will miss the U.S. Open, while Raonic, out since injuring his hip at Wimbledon, has declared himself fully healed but at this late stage has yet to say he will play. But expect more aches and pains to arise during the U.S. Open, especially if the weather is hot and humid the first week.

It has been a similar attrition rate for the women. About 14 of the top 40 have missed an event or retired with injury since the hard-court summer began in earnest four weeks ago -- but with more serious and high-profile consequences. The two-time defending champion, Kim Clijsters, is already out of the U.S. Open with an abdominal injury she experienced during her opening match at the Rogers Cup in Toronto two weeks ago -- a big blow for the event.

There were a number of pullouts in Cincinnati, with Serena Williams being the most publicized -- but also least serious. The official reason was a toe injury aggravation, which she described as a "blessing in disguise" for the U.S. Open after a summer schedule that included victories at the Bank of the West Classic in Stanford and in Toronto.

"I have more opportunity to rest up and get 200 percent healthy, which could be a very dangerous thing," she said.

Later that day, Williams visited the nearby Kings Island amusement park before leaving to attend the wedding of Kim Kardashian and Kris Humphries that weekend.

Other withdrawals included Victoria Azarenka (hand) and Shuai Peng (hip), with Venus Williams (viral illness), Agnieszka Radwanska (shoulder, back), Dominika Cibulkova (abdominal), Bethanie Mattek-Sands (shoulder) having all pulled out before the tournament began. Andrea Petkovic refused to quit and played her semifinal match with heavy strapping after suffering a tear in her knee.

All the injuries and upsets mean a lot of big names at the New Haven Open and Texas Tennis Open in Dallas this week. Marion Bartoli, Daniela Hantuchova and Maria Kirilenko, who have all had some problems, are in New Haven. More inexplicably, so is Radwanska, who said in Toronto she was "falling apart" from too much tennis and then tried to play Cincinnati before pulling out. She been in good form this summer and could be a threat to go deep at the U.S. Open -- if she can hold up physically. Peng and Cibulkova are returning at Dallas.

Most are expected to play at Flushing Meadows, though the precise fitness of significant contenders like Petkovic, Venus and Azarenka remains unclear.

One thing is for sure: Whatever shape they arrive in, players will be making their maximum effort when the year's final major begins. "It's a Grand Slam," Fish said. "It's the culmination of a long summer and a long year kind of where I know I have a few weeks off after it. You just give it everything you've got."

Kamakshi Tandon is a freelance tennis writer for ESPN.com.