U.S. Open 2015: What to watch in New York, aside from Serena

    (CNN)Trying to become the first player in 27 years to win all four grand slams in the same season, much of the attention ahead of the U.S. Open justifiably focuses on Serena Williams.

    But besides the American's quest to emulate Steffi Graf in 1988, there's plenty more to watch in New York, including these five story lines.
    The Kyrgios fallout
      After issuing Nick Kyrgios with a $10,000 fine in the immediate aftermath of his lewd sledge -- directed at Stan Wawrinka at the Coupe Rogers in Montreal -- men's governing body the ATP promised to investigate the matter further.
      And on Monday, the ATP said it would ban the Australian for 28 days and fine him a further $25,000 if the 20-year-old misbehaves in the next six months.
      Case closed?
      Maybe from the ATP's perspective, unless Kyrgios re-offends.
      But the issue is sure to rage on as the world's press descends on New York.
      Kyrgios was widely booed and lost his only match following the incident, to John Isner, so one question will be: How will the fans at Flushing Meadows treat him when he encounters Andy Murray in a blockbuster first-round clash?
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      Kyrgios' antics are, unfortunately, overshadowing his ability. He reached the Australian Open quarterfinals despite struggling with a back injury, advanced to the third round at the French Open and made the fourth round during his tumultuous Wimbledon.
      Wawrinka, meanwhile, is seeking a second major in 2015 and third overall.
      If he wins the U.S. Open, the Swiss would pass Murray on the grand slam ladder.
      The tribulations of 'Rafa'
      Rafael Nadal supporters who are seeking a boost, take heart in this statistic: In his last five visits to the U.S. Open, the Spaniard has reached at least the semifinals every time and won it twice.
      Entering 2015 the U.S. Open has been the 29-year-old's second most successful major, too, behind the French Open.
      His two titles equal his output at Wimbledon, although his winning percentage -- again, ahead of the current campaign -- in New York is superior.
      And while a 41-8 record in New York is level with his pre-2015 Australian Open tally, Nadal -- who missed last year's U.S. Open because of a wrist injury -- has bagged just one major "Down Under".
      With those impressive numbers, another premature exit from a grand slam -- Nadal hasn't advanced to a semifinal at a major this year -- would surely increase the number of onlookers who believe the "Rafa" of old won't ever reappear.
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      Nadal's hard-court results in August didn't hint at an upturn.
      In Montreal, the 14-time grand slam winner fell to U.S. Open finalist Kei Nishikori for the first time in their eight duels. When Nadal exited to countryman Feliciano Lopez in the third round in Cincinnati the following week, it marked the fourth time in 2015 he lost after snaring the first set; for three seasons from 2007-2009, Nadal lost four matches in total from that winning position.
      If Nadal manages to make the quarterfinals, waiting for him will likely be Novak Djokovic.
      Djokovic going for No. 3 in '15
      Djokovic overcame a hurdle at Wimbledon: For the first time since 2011, he won two majors in the same season. Djokovic dominated in patches in 2012, 2013 and 2014 yet lost five of his eight grand slam finals.
      This year Djokovic has reversed his fortunes, capturing two of his three grand slam finals, and triumphing in another grand slam final next month would see the world No. 1 match his haul of four years ago.
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      Simply by getting to the last stage, Djokovic would become the second man in 45 years -- after Roger Federer -- to make four grand slam finals in a calendar year.
      Regarded as the top hard-court performer on the men's tour, some would say Djokovic is due for a victory at the U.S. Open since his last -- and lone -- success came in 2011.
      He'll be the favorite in New York, even though he failed to win in Canada and Cincinnati and complained of an arm injury.
      Halep bids to end slam slump
      There are, in case you forgot, other players on the women's tour besides Williams. The next best one -- at least according to the rankings -- is Simona Halep.
      Halep has endured a highly eventful season. She landed the most prestigious title of her career at Indian Wells, and that after the death of her cousin; slumped at the French Open and Wimbledon; and cut ties with another coach, this time Victor Ionita.
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      Achieving finals in Toronto and Cincinnati signaled a return to form for the popular Romanian but questions remain about her ability to peak at the grand slams.
      Since appearing in the Wimbledon semifinals last year, Halep has exited prior to the fourth round three times. And when she did surpass that, at the Australian Open in January, she was upset by Ekaterina Makarova.
      Bouchard's shot at redemption
      Last year's success for Canadians on the tennis tour hasn't been duplicated in 2015. In the case of Milos Raonic, a foot injury dented the progress of the 2014 Wimbledon semifinalist.
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      Nagging injuries have also hurt Eugenie Bouchard, but even with the health issues -- which weren't considered too serious -- the Montrealer's poor results have been both surprising and alarming. The downturn prompted Bouchard to quit working with coach Sam Sumyk, having teamed up with him in February.
      Reaching the 2014 Wimbledon final and making semifinals at the French Open and Australian Open contributed to the 21-year-old soaring to fifth in the rankings last October.
      Now she sits 25th after winning nine of her 26 matches this season. None of the victories have come against top-30 opposition and in her most recent loss Monday, Bouchard won one game against Roberta Vinci at the Connecticut Open.