Serena Williams approaches finish line as US Open begins

One of the greatest careers in tennis and professional sport will approach its glittering conclusion as Serena Williams prepares for a possible farewell at the US Open, which begins on Monday.

The American grand slam could be the final tournament of Serena's stellar career as she announced last month her pending retirement but did not confirm the US Open as her final event.

It sets the stage for what could be an emotional farewell for Serena, who faces unheralded world number 80 Danka Kovinic in Monday's first round at the Arthur Ashe Stadium.

Serena won the first of her 23 Grand Slam singles titles as a 17-year-old at the 1999 US Open, beating Martina Hingis in the final.

That breakthrough victory confirmed what had become apparent ever since her professional debut four years earlier: that Serena, alongside sister Venus, was a rising force in women's tennis.

While 1999 marked her first singles Slam, by then Serena had already won mixed doubles titles at Wimbledon and the US Open in 1998.

Her win in the 1999 singles final would ignite the most dominant career of any female player in the Open era, her 23 Grand Slam titles second only to Margaret Court's 24.

While a record-equalling 24th Grand Slam singles title is likely to remain beyond her next week, Serena has nevertheless produced a collection of records that in all probability will never be broken.

Japanese star Naomi Osaka paid tribute to Serena, hailing the American as the "biggest force" in tennis.

Osaka, who denied Serena a record-equalling 24th Grand Slam in the stormy 2018 final in New York, said she had been left in tears by the thought of the retirement announcement.

"I think that her legacy is really wide to the point where you can't even describe it in words," Osaka said.

"She changed the sport so much. She has introduced people that have never heard of tennis into the sport. I think I'm a product of what she has done. I wouldn't be here without Serena, Venus, her whole family. I'm, like, very thankful to her.

"I honestly think that she's the biggest force in the sport. That's not intentionally trying to make [Roger] Federer or [Rafael] Nadal smaller. I just think she's the biggest thing that will ever be in the sport.

"It's just really an honour just to watch her play. She's giving us a chance to watch her more."

On the men's side, Rafael Nadal will target a fifth US Open and 23rd Grand Slam title in New York with his path to the title no longer blocked by Novak Djokovic, whose refusal to be vaccinated against Covid-19 has ruled him out of a second major this year.

The Spaniard has had to sit out the US Open four times in his career and there are once again fresh doubts over his physical ability to survive a gruelling two weeks at Flushing Meadows.

Nadal admitted that he had been protecting his injury in Cincinnati but had been able to practise with intensity in the build-up to the US Open.

"I take it very easy in the Cincinnati, too, in the practices. The match, I try my best without putting all the effort there on the serve," Nadal said.

"I hope to be ready for the action. That's the only thing that I can say.

"Taking care with the serve, being honest. But in general terms, yes, I am practising at high level of intensity."