Serena Williams and Novak Djokovic arrived at the US Open as the top seeds and favorites to win, but both are nursing injuries.
Williams is recovering from a sore right shoulder that forced her to withdraw from a Cincinnati event last week. Djokovic has a left wrist issue that may have contributed to his loss to Juan Martín del Potro in the first round at the Rio Olympics.
This is a far different entrance into the US Open than Williams and Djokovic made a year ago.
Each surged into the tournament in 2015, with Williams on a highly publicized quest to win the Grand Slam, and Djokovic in search of his third major title of the year. Djokovic collected his championship, but Williams came up short of her goal.
Now, attention will focus squarely on how they are able to negotiate through their maladies, at least in the early rounds.
"It wasn't very easy, I think, physically," Williams said of her past few weeks. "I was just trying so hard and trying everything to get better. At the end of the day, I knew I gave the best effort I could, and it just wasn't enough."
Williams said that her sore shoulder first cropped up the day after she won Wimbledon in July. Then she went to the Olympics and suffered an uncharacteristic third-round loss to No. 20 Elina Svitolina, 6-4, 6-3.
Just two months earlier, Williams had pounded Svitolina, 6-1, 6-1 at the French Open.
"At the Olympics, I just practiced two days before playing my match," she said. "It's not ideal, but it was all I could do."
As is usually the case with Williams, there is a lot at stake. There is no Grand Slam to tantalize her, but if she wins the Open, she will pass Steffi Graf with her 23rd major tournament victory, an Open-era record.
She would also pass Chris Evert for the most US Open singles titles with seven. At the same time, she is fighting to maintain her long hold on the No. 1 ranking.
Last week, Williams went to Cincinnati intent on protecting her No. 1 ranking against an assault by Angelique Kerber, who is No. 2. But after an uncomfortable practice there, the aching shoulder forced Williams to withdraw.
Kerber could have passed Williams in the rankings if she had won in Cincinnati, but Kerber lost in the final to Karolina Pliskova. Depending on how each fares at the US Open, Kerber can still end Williams' reign at No. 1. Williams has held the top spot for 183 consecutive weeks, three short of Graf's record.
Williams was handed a challenging first-round matchup against Ekaterina Makarova, ranked No. 36. Williams holds a 4-1 advantage over Makarova, who beat Williams at the 2012 Australian Open. They also met in the semifinals of the 2014 US Open.
Balancing act
Williams said her shoulder was starting to feel better, but she was trying to balance the need for rest with the need to practice.
Her coach, Patrick Mouratoglou, said he did not believe that the shoulder would hamper Williams' pursuit of her 23rd Grand Slam singles title, which would leave her one short of Margaret Court's overall record.
Although Williams has not played often since Wimbledon, Mouratoglou pointed out that she was competing in two events in each of the last four tournaments she entered, which may have taken a toll.
"I am not concerned about the shoulder," Mouratoglou said. "She was playing both singles and doubles at Wimbledon and the Olympics, and that is not easy. But she is working hard and recovering well."
Djokovic, who won the Australian and French Opens this year, did not cite a precise diagnosis for his wrist injury. He noted the coincidence of playing in Rio against del Potro, who missed three years on the tour with a left wrist injury that required multiple surgeries. Djokovic called the wrist "that essential part of your body as a tennis player."
"The wrist hasn't been in an ideal state for the last three and a half weeks," he said. "But I'm doing everything in my power with the medical team so I'm as close to 100 percent as possible, at least for the beginning of it."
Djokovic said the injury occurred while he was practicing in Rio, stressing that it was not the reason for his earlier loss to Sam Querrey in the third round at Wimbledon. But Djokovic did say he was dealing with an unspecified personal problem at Wimbledon.
"We all have private issues," he said, adding that the matter had been resolved. But the wrist injury is not, and Djokovic, who ended his practice early on Friday, said he was trying a variety of methods to make it heal faster, including electrical stimulation.
"Sometimes time is what you need as an athlete, and the US Open is around the corner and I don't have much time," Djokovic said. "I try to compensate and improvise as much as I can and find the best ways of getting myself properly ready."