Six players to watch at the U.S. Open

No Roger Federer, out with a knee injury. No Serena Williams, out with a hamstring injury. No Rafael Nadal, out with a foot injury. For the first time since 1997, those three tennis legends will not play in New York for the final Grand Slam tournament of the year.

Venus Williams also pulled out for health reasons; the defending men's champion Dominic Thiem is out with a wrist injury; and the top American woman, No. 5 Sofia Kenin, withdrew after testing positive for COVID-19.

But there is still history on the line when the tournament begins Monday. Novak Djokovic is attempting to become the first player since Steffi Graf in 1988 to complete a Grand Slam, winning the Australian Open, the French Open, Wimbledon and the U.S. Open in the same year. The last man to do it was Rod Laver in 1969.

NOVAK DJOKOVIC

Ranking: 1 | Grand Slam titles: 20

There is little doubt Djokovic, 34, remains the favorite, despite the fact he hasn't played since losing in the semifinals at the Olympics, has been a little banged up and was last seen on the tennis court having a racket-smashing tantrum during the bronze medal singles match in Tokyo. He has not shied away from talking about his history-making season, but strange things tend to happen in New York when expectations are sky high. He was an overwhelming favorite at last year's U.S. Open with Federer and Nadal out, but was defaulted in the fourth round after hitting a line judge with a ball. And the last player to get this close to a Grand Slam was Serena Williams in 2015, when she had a shocking loss to Roberta Vinci in the semifinals. Oh, by the way, a U.S. Open title would also give Djokovic 21 Grand Slam singles championships, breaking his tie with Federer and Nadal for the men's record.

ALEXANDER ZVEREV

Ranking: 4 | Grand Slam titles: 0

Thiem is missing the U.S. Open, but the player he beat in the 2020 final, Zverev, is the hottest player on the tour. He is on an 11-match winning streak, claiming the Olympic gold medal (beating Djokovic in the semifinals) and the Cincinnati Masters last week. He is in Djokovic's half of the draw in New York, giving him a chance to derail Djokovic's Grand Slam quest in the semifinals. Off the court, though, domestic abuse allegations from a former girlfriend are back in the news. Zverev, a 24-year-old German, has repeatedly denied the accusations, but the story line figures to loom over the tournament as long as he's in it.

DANIIL MEDVEDEV

Ranking: 2 | Grand Slam titles: 0

The second-ranked Medvedev has been one of the most consistent hard-court players over the past three years, reaching the final of the 2019 U.S. Open (losing to Nadal) and the 2021 Australian Open (losing to Djokovic) and winning the 2020 ATP Tour Finals. Recently, the 25-year-old Russian won the Canada Masters in Toronto this month and was a semifinalist in Cincinnati. Fans are in the stands at Flushing Meadows for the first time since 2019, when Medvedev first earned their ire for his on-court temper, then won them over with a spirited run to a five-set final against Nadal.

ASHLEIGH BARTY

Ranking: 1 | Grand Slam titles: 2

The top-ranked Barty, 25, has been a steady force on the women's tour in an unpredictable season. She has won five titles on three surfaces, including at Wimbledon in July and in Cincinnati last week. She has reached the final in six of the 12 tournaments she has played, compiling a 40-7 overall record. The Australian has never advanced past the round of 16 at the U.S. Open, but did not play the tournament last year because of the pandemic.

NAOMI OSAKA

Ranking: 3 | Grand Slam titles: 4

Osaka, 24, is arguably the best hard-court player on the women's tour. She is the defending champion at the U.S. Open, which she has won twice, and claimed the last hard-court major in Australia in February. But since then, her season has been a roller coaster. She took a two-month mental health break after pulling out of the French Open. She returned for the Tokyo Olympics, where she lit the cauldron at the Opening Ceremony and then lost in the third round. At the Cincinnati event last week, she gained an impressive win over Coco Gauff in her opening match, but fell to little-known Jil Teichmann in her second. Teichmann ended up making the final, defeating three top-10 players on the way, lessening the blow on Osaka. Still, she is a big question mark heading into this tournament.

KAROLINA PLISKOVA

Ranking: 4 | Grand Slam titles: 0

The 29-year-old Czech is in the conversation when talking about the best current player never to win a major. A former No. 1, Pliskova was up a break in the third set of the 2016 U.S. Open final against Angelique Kerber but lost the match. At the time, though, it seemed many more Grand Slam finals were in her future. But she did not return to a major final until Wimbledon this past July, when she lost to Barty. Pliskova's booming serve is a perfect fit for hard courts, and she has continued her strong play this month, reaching the final in Montreal and the semifinals in Cincinnati.