For the ninth time since the game turned professional in 1968, the top four women's seeds have advanced to the semi-finals at Wimbledon.

Serena and Venus Williams, Kim Clijsters and Justin Henin-Hardenne are also ranked the top four players in the world and as polarised as any group could be.

No one has ever believed that top players exchange comfort text messages, and there is a long history of fractious relationships between elite athletes and their closest rivals. Martina Navratilova and Chris Evert famously disliked each other, and while Tim Henman and Greg Rusedski present a serene public face, their relationship is said to be on the frigid side of cool.

Today, when Serena and Henin-Hardenne walk on to Centre Court, it will be difficult to disguise the frisson of animosity that exists between the world number one and number three players. Despite the 21-year-old Belgian having metaphorically waved a piece of paper in her hand and muttered "peace in our time" after her quarter-final, the die has been cast.

The racist undercurrent from the crowd, when they booed Serena off the court at Roland Garros after she had been beaten in the semi-final by Henin-Hardenne, was just four weeks ago. Williams's mother, Oracene, also became involved, such was the vitriol, and she famously condemned the French crowd as having "no class" and displaying "ignorance".

To add insult to injury, Henin-Hardenne then grabbed the crown to deprive Serena of five successive Grand Slam wins. The last contact was a cursory touching of hands between a smiling Henin-Hardenne and a seething Williams.

Henin-Hardenne also grew up with Kim Clijsters, and despite being from different parts of the country (Clijsters is Flemish and Henin-Hardenne Walloon), they have a shared past of playing in junior events around the world.

Clijsters has not become embroiled in the saga, but her opponent, Venus, has clearly and understandably aligned herself with her sister. When Serena was 5-2 down in the first set against Jennifer Capriati in the quarter-final, the elder Williams was asked, if Serena were beaten, would it give her greater motivation to win the championship.

"I don't know," she said. "I don't want words put in my mouth. But of course if I can't do it for myself, then I'll do it for Serena."

The two Belgians also understand that they are meeting Venus and Serena on a surface the Americans enjoy and with the pair at the top of their games.

While Clijsters, in her last match, dropped the first set 5-7 to Silvia Farina Elia after being stung on the stomach by a bee, she then turned her opponent over 6-0, 6-1.

But she has had a dangerously trouble-free run to the semi-final. Prior to her fourth-round match, she'd lost only seven games. Such a sequence without a credible dog-fight will require Clijsters to discover a significantly higher level on demand. Venus was stretched by Lindsay Davenport, but the fear in the Belgian camp is that Clijsters has had no such examination.

"I had to fight very hard," said Venus. "It was a tough match and I knew it was going to be because Lindsay was striking the ball so clean the whole tournament. But it helped me a lot that I'm able to play good defence and also a lot of good offence, and then take the offence and make it defence."

They have played almost the same number of games, Clijsters 85 to Williams 87, with Venus spending almost an hour longer on court getting there. Clijsters demonstrably has the muscle not to be broken by the size of Williams game, but any first-set lapse or no-shows, as in the French Open final, and the world number two could ignominiously depart in two sets.

Henin-Hardenne has a proven toughness and poise neatly packaged into a wispy physique, but her history of defeats here, losing to Venus in the 2001 final and Serena in last year's semi-final, should not overshadow the confidence gleaned from winning the French Open. She has also declared that she won't wait for things to develop but will fearlessly attack. Tactics straight out of the Williams's manual.

Serena's high unforced-error count, garishly illustrated in her first set against Capriati, is her principle weakness, while her serve, which pulled her out of trouble in that match, is a tournament winner.

Serena also seems confident that her more contained game on Centre Court in the semi-final of the biggest tournament in the world will right Parisian wrongs. But typically she remained coy. France, she claimed, was a long time ago and she didn't remember the booing, cat calls, recrimination and tears.

"She (Henin-Hardenne) won the French. She played very well. So I don't think she should have any regret about winning the French. That was a long time ago. I don't even remember," she said.

"It's fine playing against a crowd that's going against you, it's just a little tough to play against people that are booing in between first and second serves," she added, becoming irritated. "Come on, this is getting difficult."

That's it then. No personal animosity, no revenge, no Roland Garros hangover, no Belgian-American divide. Just another Wimbledon semi-final.