NEW YORK, USA (AFP) — Serena Williams played down the praise of her rivals as the best player in women's tennis history and the US Open favourite, saying she feels no pressure coming off Wimbledon and Olympic titles.

"You've got to embrace it whether you're the favourite or whether you're not. And I embrace it," Williams said. "In Wimbledon I wasn't the favourite. I embraced that. Hopefully, I can do my best here."

Williams seeks her 45th career crown and 15th Grand Slam title. She has won five tournaments this year, including Charleston, Madrid, Stanford plus the London Olympics and Wimbledon, her first Grand Slam title since 2008.

"Serena is playing incredibly well," three-time US Open winner Kim Clijsters said. "She has switched someting on. She's fitter than ever. It's great to see somebody who has won so much and who is still focused on winning.

"Serena is just the greatest ever. Physically when she's in shape she just stands out — she's fast, she's strong, she has a good eye. What she has shown in the past few months is she's the best player ever."

Williams argued the point, saying those with record numbers of titles should be given the nod such as Margaret Court or Steffi Graf.

"I can't sit here and say I'm the best ever. I'm not. I'm not worthy of that title," Williams said. "I'm just Serena. I love playing tennis and I'm good at it. Just because I'm good at it doesn't make me the best."

Fourth seed Williams gave the favourite's nod to defending champion Samantha Stosur, who beat her in last year's final, and top seed Victoria Azarenka, the reigning Australian Open champion.

But Stosur and Maria Sharpova, who completed a career Grand Slam by winning this year's French Open, gave Williams the favourite's tag.

"She gained a lot of confidence at Wimbledon. With every match she just improved," Sharapova said. "Of course she's the favourite. But everybody is still in the draw."

Former World No 1 Williams said such labels add no pressure to the challenge she faces.

"I don't put any pressure on myself," Williams said. "If I win, that would be great. If I lose, I realise I'm going to go home and be devastated. But there's always tomorrow."

She did, however, grow testy when asked about her celebration dance at the Olympics, one known as the "Crip Dance" that drew some unwelcome attention.

"It was just a dance. I didn't know that's what it was called," Williams said. "Why are you asking me that? If anything you should be trying to ask me questions to lift me up not bring (up) such things."

Since beating her sister Venus in the 2002 final, Williams has won the US Open only once, in 2008.

Williams, 30, opens against US compatriot Coco Vandeweghe in a rematch of last month's Stanford final. Williams had won 19 matches in a row until the streak was snapped in the Cincinnati semi-finals by Germany's Angelique Kerber.