TENNIS

10 things to watch at U.S. Open as Murray, Djokovic face challenges

Nick McCarvel
Special for USA TODAY Sports
Andy Murray (GBR) reacts against Milos Raonic (CAN) in the semifinals during the Western and Southern tennis tournament at Linder Family Tennis Center.

NEW YORK CITY – Just days after the biggest sporting event in the world – the Olympics – came to a close in Rio, the U.S. Open takes center stage, set to begin Monday in Flushing Meadows, Queens.

The tournament will be without Roger Federer for the first time since 1999, but Novak Djokovic, Andy Murray, Serena Williams and others will vie for one of tennis’ four most coveted trophies under a newly finished roof inside Arthur Ashe Stadium.

Here, a look at the 10 storylines you can’t miss over the next two weeks.

Serena goes for No. 23 — and tries to stay atop rankings

There is no epic chase for the calendar Grand Slam like in 2015, but world No. 1 Serena Williams will look to break another record at this year’s Open: Steffi Graf’s 22 majors in the Open era. Williams will not only go for No. 23, but she’ll also try to extend her streak of weeks at No. 1 to 187, which would break another record held by Graf.

Djokovic the favorite, or not?

Two months ago, after Novak Djokovic’s French Open domination, the tennis world wondered: Can this guy go 4-for-4? But then the Serb uncharacteristically went out in the third round of Wimbledon to American Sam Querrey and was shocked in the first round of the Olympics by Juan Martin Del Potro. Djokovic is human, after all, and will now face a stiff test from foes who see an opening, with the world No. 1’s confidence shaken.

Look up, it’s a roof

The USTA’s $150 million retractable roof makes its debut at this year’s Open, making it the third of the four majors to have a covered court if need be. (The French Open lacks one, as a rainy 2016 tournament drearily highlighted.) After recent rainy years leaving the schedule backlogged in New York, organizers will take solace (and cover) under the roof, which uses 13 million pounds of steel and stretches over 62,500 square feet.

Puig and Del Potro: Olympic glow flickers on?

Monica Puig was arguably the story not just of tennis in Rio, but of the entire Olympics after the unheralded Puerto Rican ranked No. 34 shocked for the women’s gold over Angelique Kerber, winning the first gold medal for her country. She and Del Potro will head to New York hoping to emulate their respective Rio successes, Del Potro an unseeded danger in the first round and Puig the last to be seeded after American Sloane Stephens withdrew Friday. Del Potro had a fairy-tale run, shocking Djokovic in round one, then beating Rafael Nadal in a classic semifinal and eventually succumbing to Murray for the silver medal.

Who else to fear?

Kerber will lead a slew of women chasing Serena’s No. 1 ranking, as she, French Open champion Garbiñe Muguruza and Agnieszka Radwanska could all overtake Williams. Madison Keys, the American, is always a danger, as is Venus Williams at 36. Puig, Simona Halep, Petra Kvitova and 2015 Serena-slayer Roberta Vinci are capable of deep runs in a women’s field that is without Victoria Azarenka, who announced her pregnancy last month.

The men to challenge Djokovic are a red-hot Murray, who has won 22 of 23 matches, as well as Cincinnati winner and 2014 Open champ Marin Cilic, a resurgent Nadal (who won gold in Rio in doubles while placing fourth in singles), Wimbledon semifinalist Milos Raonic, two-time Slam champ Stan Wawrinka and Kei Nishikori of Japan, who won bronze in Rio.

Madison Keys on failing to medal in Rio: 'It still kind of kills me'

We’ll miss you, Roger

Federer called it quits for the 2016 last month after a series of mishaps this season: A fluke accident led to knee surgery; a stomach virus knocked him out of Miami; a bad back put him out of the French Open. It is the knee, however, that forced him to pack up his racket bag, now eyeing a return in the Australian summer in January. The 17-time major champion is out of the U.S. Open for the first time since 1999, and said earlier this week it pained him to be in New York as the tournament goes on without him.

Venus keeps plugging away

You can’t help but wonder: Is this Venus Williams' final U.S. Open? It’s a question that has followed her for much of the past five years, after she announced in 2011 that she was suffering from Sjogren’s syndrome, an energy-sapping disease. But she was a semifinalist at Wimbledon this year, is seeded No. 6 for the Open and two weeks ago won the mixed doubles silver medal in Rio alongside Rajeev Ram. Will Williams be at Tokyo 2020? “I imagine if I really wanted to be there I could. … I’m going to have to want to do the work. We’ll see.” So let’s just wait and see – and appreciate Williams for her legacy as she continues to compete and wade into tennis territory uncharted.

A whole new grandstand

It’s not just the roof over Arthur Ashe Stadium that’s making its Open debut, there is also a new Grandstand stadium, replacing the court that many called their favorite in tennis. The old Grandstand sat adjacent to Louis Armstrong Stadium and was an intimate, tree-shadowed court with impeccable sight lines. The USTA has tried to keep that intimacy in the new Grandstand court, which is situated on the opposite side of the grounds of the Billie Jean King National Tennis Center. The sunken court seats 8,100 (up from 5,800 at the old Grandstand) and is hexadecagonal in shape (16 sides), with a shade canopy of fabric covering two thirds of it for further fan enjoyment.

Who's got xext?

It’s the annual game of “Who is the next American tennis star?” Keys, 21, is the most well-established and embedded in the top 10 and coming off a fourth-place finish in Rio. Taylor Fritz is 18 and ranked No. 54 in the world and with a lightning bolt of a serve that's part of his go-for-broke arsenal. Louisa Chirico and Samantha Crawford have had spurts of success this year, while Jared Donaldson and Francis Tiafoe are also looking for respective breakthroughs.

Meanwhile, Steve Johnson briefly took over the No. 1 American spot from John Isner on the men’s side, as mid-major lurkers like Jack Sock, Querrey and Donald Young continue to look for a masterful major, though they often appear to be punching above their weight against the best in the world.

An absent Sharapova as tennis continues crackdown

Tennis has continued to prove it has no room for PEDs in the sport, a tribunal suspending Maria Sharapova earlier this year for two years after it was revealed she took the banned substance meldonium. Earlier this week the International Tennis Federation announced that it would do away with “silent bans,” as well, solely due to the lack of transparency said bans encourage. Silent bans had been used inside the sport when “atypical” or “adverse” findings were revealed in drug tests (most often traces or very little amount of a substance), protecting the player from media scrutiny. But, that policy is no longer in place, meaning any ban – no matter for what or for how long – will now be public.

And as for Sharapova? Her appeal on the two-year ban is being reviewed by the Court of Arbitration for Sport, with a decision to be handed down by Sept. 19 at the latest.