Serena Williams might today match the 22 Grand Slam singles titles won between 1987 and 1999 by Steffi Graf.

We are, no question, in the presence of one of the greatest female tennis players, indeed sports stars, ever.

But don't say that to her. A journalist made that mistake after her semi-final win on Thursday. He asked how it felt to be regarded one of the greatest female athletes ever.

"I prefer 'one of the greatest athletes of all time', " she responded.

It came after Williams had blown her Russian opponent Elena Vesnina off the Centre Court in just 48 minutes. The score was 6-2, 6-0, and the American allowed her opponent to score just one point off her first serve.

Beating wasn't the right term. Obliterating would be closer.

Serena's qualification of her worth is about the touchy subject of what the Americans call "gender specification".

It's taboo to go there, and when Ms Williams is in the room, maybe not wise.

She is what she is. And if there was always a hint of humour about Muhammad Ali's "I am the Greatest" box office boast, sister Williams leaves no such impression.

How dare anyone question her in any way?

Reaching a third Grand Slam final this year, someone said, is an impressive achievement. "I think for anyone else in this whole planet," she answered, "it would be a wonderful accomplishment.

"For me, its about holding the trophy. For me, it's not enough. But I think that's what makes me different. That's what makes me Serena."

Okay, give her that. She clearly intends to take it anyway, although her Wimbledon opponent today happens to be Germany's Angelique Kerber, who beat Serena in the Australian Open final in January.

Rain permitting, it could be quite a testing afternoon.

But the weather has already sparked something in Serena (better to use that name because her big sister Venus is still good enough to have reached the other semi-final before being knocked out by Kerber).

Earlier this week, there was a hint of rain in the air when Serena played her fourth-round match against Russia's Svetlana Kuznetsova on Tuesday.

The first set stood at 5-5 all. Serena had slipped on the grass when a Kuznetsova winner wrong-footed her.

The American asked for play to be suspended and the roof closed. The umpire Marija Cicak came down from her chair to discuss the request.

"I'm going to fall," Williams said. "I don't get it. Can't they just close the roof."

Cicak consulted the other player. Kuznetsova said to both the umpire and the tournament referee: "You take the decision, I am here to play."

At that stage, Williams was heard telling the umpire: "If I get hurt, I'm suing."

This was the second time this week a player had made that threat. Frenchman Gilles Simon had been the first.

Here you have a terrible dichotomy. The players are, by far, wealthier than tournament officials. Serena Williams' career prize money tops US$78 million (S$105.2 million) - and that is just for time on court.

It doesn't take into account the millions that companies pay to associate with what she wears, how she smells, and smiles and breathes.

So, self evidently, any legal threat is going to be taken extremely seriously.

And when that threat is made, the game is in serious trouble.

Simon later insisted that "obviously" his game was playing tennis and he would never follow through on the threat. Serena made no such retraction untilshe faced the press later.

What she did concede is that during the break while the match was postponed (in contrast to every other game playing on, including that involving her sister Venus on uncovered courts), it really helped to talk to her coach Patrick Mouratoglou. He calmed her down.

When play resumed, Serena polished off the first set 7-5 and swept the second 6-0.

That form has rolled on.

While the weather behaved for the rest of the week, Williams was untouchable. Her semi-final starkly contrasted with the marathons which took Andy Murray five sets and three hours to overcome Jo-Wilfried Tsonga, and Roger Federer to come from two sets down to overhaul Marin Cilic.

The principle of equal pay and the equality of the sexes is now long established. Wimbledon was the last tournament to concede to the demands led by Billie Jean King in the 1970s.

The issue came back briefly when an elderly tournament director (male) was forced to resign after unwisely saying that women pros should "get down" on their knees "every night" and thank Roger Federer and Rafael Nadal for carrying the sport.

"It's more about what's morally the right thing to do over time," King commented on CNN. "We can set a great example about getting the gender gap and salaries even. Sport is a microcosm of society and it's important sports people take responsibility and step up and lead."

Whether sport is a true microcosm of anything any longer is open to question. Players get more in two weeks than many workers get in a year, or maybe 10 years.

That is not to suggest that Serena Williams is not entitled to her points.

"I would like to see people - the public, the press, other athletes in general - just realise and respect women for who they are and what they do," she said at her press conference after the semis.

"I've been working at this since I was three years old. I haven't had a life. I don't think I deserve to be paid less because of my sex."

I must argue. She might sue.