Sharapova sets out to retain her US Open title after a year dogged by worrying injuries

"It's what everybody wants to know," the announcer said at the exclusive gathering on the rooftop of the Rockefeller Center. "What's Maria going to be wearing at this year's US Open?"

On cue, Maria Sharapova bounced on to the makeshift stage at The Top of the Rock in the "knee-length atomic red dress with a simple flared shift silhouette" (pictured right) that she will wear at night matches (the defending champion's Nike designers have come up with a more modest black-and-white number for day contests) at the year's final Grand Slam tournament, which begins here today. The dress also features 600 encrusted Swarovski crystals which, we were told, "literally and figuratively represent the backdrop of New York at night".

Sharapova posed for photographers with the self-assurance of a woman who is clearly at ease on the catwalk. However, just when you were wondering what any of this had to do with tennis, her response to the first question from the assembled fashion reporters reminded you that the Russian knows perfectly well when business has to come first. "Now that you're here in New York, will you be going to any Fashion Week events?" she was asked. "I'd love to," Sharapova replied. "After the tournament."

Tennis is littered with tales of young women who have found lives away from the court or burnt themselves out before their mid-twenties. It may yet happen to 20-year-old Sharapova, though for the moment the dangers appear to be physical rather than mental; her year has been dogged by injury and she needs a successful tournament over the next fortnight to retain her world No 2 ranking after winning only one title on the Sony Ericsson tour in the last 10 months.

Sharapova has become a one-woman marketing phenomenon. The Russian and glossy magazines go together like Manhattan and skyscrapers, with sponsors bewitched by her combination of winning tennis, good looks and sparky personality.

In a nation which enjoys measuring such things, she has been named the planet's highest-paid sportswoman, having earned more than $23m (about £11.5m) last year, and one of its leading celebrities. This year's Forbes Celebrity 100 list, which was topped by Oprah Winfrey, featured just three tennis players: Roger Federer (at No 38), Sharapova (51) and Serena Williams (69).

Sharapova clearly enjoys her beauty, fame and ability to make money, as well as the chances to mix in celebrity circles. After picking up two honours at last month's Excellence in Sports Performance Awards at a glamorous ceremony in Hollywood, she seemed to relish relating the story of how she had met Paris Hilton, who asked her where she had got her dress. "In Paris," Sharapova replied.

There are, of course, downsides. It is hard to imagine as much press interest in any other tennis player as was shown recently when a former "boyfriend" supposedly talked about Sharapova's performance in the bedroom; considerably fewer column inches were devoted to the subject when his publicists later denied that he had made the comments and said that he had met her only once, at her birthday party two years ago.

Not surprisingly, Sharapova rates New York her favourite city in the world. "It has a buzz," she said. "I've had a meal at a different restaurant every single night and I haven't had a bad meal. I'm a big food fan. Every year I come back to find 10 new restaurants to go to, so that's always fun. And the shows..."

Nevertheless, she was quick to shoot down any talk of conflicting priorities. Asked whether the "fashion shoots and parties" had affected her preparations for the tournament, she retorted: "I did two events. One was for one hour and the other for an hour and a half, all in the evening after all my training. So, no."

Sharapova said she had been working hard in practice, but will she be able to handle the rigours of a fortnight-long event? A shoulder injury which has troubled her since the spring is still a concern and only two weeks ago she could barely walk, having pulled out midway through a tournament in Los Angeles with a leg injury.

Sharapova insisted she is on the mend – "I've had some really good practice sessions and I feel like I'm serving probably the biggest that I've served this year" – but some fear this year may be a taste of things to come for a woman whose leggy 6ft 2in frame may not be ideal for a tennis player. While the Russian looks appreciably stronger than when she took Wimbledon by storm three years ago, her movement around the court has never been her strong point.

Nick Bollettieri, who has watched over Sharapova ever since her father brought her to his Florida academy 11 years ago, said last week: "Maria always will be a wonderful competitor, but I do wonder whether injuries are going to be an increasing problem for her. The problem is her height. It takes so much effort for her to move and get back into position that I fear it could take a heavy toll on her body."

Max Eisenbud, Sharapova's agent, takes a more positive view. "Most of her injuries have just been nagging ones," he said. "Most of the other leading women players have had more serious injuries to contend with. Generally, Maria's injuries have happened because she's grown so much.

"Actually, I think she's been very lucky. People say this has been a down year for her because of her injuries, but she got to the final of the Australian Open and has just won in San Diego. A lot of people would love to have a 'bad' year like that."

Sharapova's win here 12 months ago was hailed as a second breakthrough – despite her great consistency she had waited more than two years to win a second Grand Slam title – but 2007 has brought some shattering defeats, including comprehensive losses to Serena Williams in the Australian Open final and to Venus Williams at Wimbledon, even if she defied all the odds to record her best performance at Roland Garros, reaching the semi-finals.

"Her dad, coaches and trainers begged her not to play the French Open because her shoulder was so bad," Eisenbud said. "They wanted her to skip Paris and prepare for Wimbledon, but Maria said: 'If I do that I won't have played for weeks and there's no chance I'll do well at Wimbledon.' So she made a deal whereby she slowed her serve down to about 90mph."

The shoulder injury also scuppered Sharapova's chances of making her long-awaited Fed Cup debut for Russia. Some of her compatriots had previously made it clear that she would not be welcome on the team, on the grounds that she had deserted her homeland long ago and is now an American in all but name, but she was selected for the ties against Spain and the United States. When injury forced her to pull out of both she was strongly criticised by some Russian officials. She has not been selected for next month's final against Italy in Moscow.

Sharapova has been forced to switch to a less demanding racket, with looser strings, and has also needed intensive treatment. She has spent two hours a day strengthening the shoulder and having it treated with ice, massage and acupuncture. She even resorted to a cortisone injection, although it is not a course of action she would like to repeat. "I want to try to stay away from the shots as much as possible," she said. "Firstly, I hate needles. And secondly I don't think cortisone is the best thing for your body, especially when you're 20 years old."

If the injuries have given Sharapova more opportunities to sample life outside tennis, she insists she enjoys the simple pleasures as much as the celebrity whirl. She has even been learning her way around her local supermarket and her own kitchen.

She is also aware of the wider world. Earlier this year she was appointed a goodwill ambassador for the United Nations Development Programme – she receives a nominal salary of $1 a year and has to pay for her own trips – and promptly donated $100,000 (about £50,000) to help recovery in the Chernobyl region. Sharapova's father and pregnant mother fled the nearby city of Gomel after the Chernobyl nuclear plant exploded 21 years ago and went to Nyagan in Siberia, where she was born. The UN has invited Sharapova to visit Chernobyl next year.

Finding time for her UN work – and everything else – has been a challenge and Eisenbud has learnt much from Tiger Woods' agent, Mark Steinberg, a colleague at IMG. "After Maria won Wimbledon I asked Mark how Tiger manages his time, because it's always been clear that winning remains the most important thing for Maria," Eisenbud said.

"The most amazing thing about her is that she very easily says no. As soon as she won Wimbledon she had so many amazing offers, but she rejected nearly all of them because she wanted to concentrate on her tennis.

"She has an unbelievable desire to compete and to win, which overrides everything else. She likes things like the fashion side, but it doesn't even come close to what tennis means to her. She's young and knows that tennis is what she wants to concentrate on for maybe the next six or seven years. She knows that there will be plenty of time for everything else after that. It's not her parents telling her that. It comes from inside."

The thrill of competition still excites Sharapova, who admitted she would be nervous when she begins the defence of her title. "Nerves are part of being an athlete," she said. "It's how you deal with nerves. I love it when there's something on the line. That's when I play my best tennis."

Sharapova's Year of Injury Woe

February Retires hurt with hamstring strain during semi-final of Tokyo tournament against Ana Ivanovic. Injury subsequently forces her to withdraw from Dubai.

MARCH Loses heavily to Serena Williams in last 16 of Sony Ericsson Championships in Miami while suffering from shoulder injury.

APRIL Withdraws from Charleston with shoulder and hamstring injuries.

MAY Withdraws from Rome with shoulder injury before returning at Istanbul.

AUGUST Withdraws from Los Angeles tournament with leg injury 20 minutes before semi-final against Nadia Petrova. Misses Toronto tournament.