Predicting the winner of the women's singles might feel like a game of pin the tail on the donkey with an extra-thick blindfold, but Serena Williams isn't ready to consign herself to the ranks of the plucky contenders just yet.

The pre-eminent champion was asked on Sunday about the difficulty of being the one they all want to beat.

'I've had a big X on my back since '99, since I won the US Open,' said the 39-year-old, with the gaze that has frozen the blood of many an opponent over the years. 

'Players play me that hard every single tournament, every single match, every single Grand Slam.

'It's been difficult mentally when someone might beat you and they lose directly in the next round almost every time. At the end of the day that's why I'm Serena. So thanks.'

It is only more recently that her aura has begun to dissipate, and players have seemed more eager to take a shot at the seven-time Wimbledon champion.

Elena Rybakina, for example, was not exactly quivering with fear as she dispatched Williams 6-3, 7-5 at the French Open.

The American begins her latest bid to equal Margeret Court's record of 24 Grand Slam titles tomorrow against Aliaksandra Sasnovich of Belarus as one of, conservatively, 30 contenders to lift the Wimbledon title.

Out of the last 17 majors only Naomi Osaka and Simona Halep have won multiple titles — and both are absent from Wimbledon this year.

Osaka is taking time to regroup after her withdrawal from Roland Garros amid her refusal to attend press conferences and mental health issues. 

Defending champion Halep scratched after she failed to recover from a calf injury.

That leaves a field that looks as wide open as any in Wimbledon history.

'The women's draw is so deep, regardless of who you play,' acknowledged Williams. 'You really have to show up now. 

'There are no longer matches that are going to be a sure walk-through. You just have to really have your head in, have your game on.'

It has been a familiar refrain, but with two rivals absent and on her favourite surface, Williams will never have a better chance of winning that historic 24th Slam.

One tournament she will not be winning is the Tokyo Olympics, as on Sunday she became the latest big name to announce that she will not be competing. 

'There's a lot of reasons that I made my Olympic decision,' she said. 'I don't feel like going into them today. Maybe another day.'

Australian world No 1 Ash Barty has already confirmed her participation in the Olympics, and she starts as the favourite for Wimbledon.

The 25-year-old Queenslander has a favourable draw, a free-flowing game suited to the lawns and three titles already this year. 

She has not played since a hip injury forced her out of the French Open, but says her rehab has gone well.

She would be a fitting champion on the 50th anniversary of Evonne Goolagong Cawley's first title here and Barty, who is part indigenous, will wear an outfit based on the dress her countrywoman wore in 1971. 

'It's a really special anniversary for a lot of Australians, but for indigenous Australians in particular,' she said. 

'For me to be able to wear an outfit inspired by Evonne's iconic scallop dress is amazing.'

Of the former champions in the draw, Petra Kvitova looks the most dangerous, although she has a horrible first-round match against 2017 US Open winner Sloane Stephens on Centre Court on Monday.

In full flight Kvitova is unstoppable on grass, and the 2011 and 2014 winner is glad to be back. 

'For the tennis world, it means a lot to be back in Wimby,' she said. 'Being back in this magical place, it's very important for everybody.'

As for British No 1 Jo Konta, while not one of the favourites, was one of the massed ranks of outsiders. 

However, the 30-year-old, who was due to start tomorrow against Katerina Siniakova, has been forced to withdraw after one of her team tested positive for Covid-19, meaning she must isolate for 10 days.