As the top four seeds rocked and staggered before eventually succumbing at SW19, there has been an increasing sense of inevitability that the Williams sisters will contest Saturday's final.

It would be the fourth all-Williams affair at Wimbledon and the third final between the duo, although they have not met on grass here since 2003.

In the intervening five years, the pair that looked set to dominate the sport with their sheer power, aggression and self-determination have seen their influence at the very top of the game drift as Ana Ivanovic, Maria Sharapova and, to a lesser extent, Jelena Jankovic take over the rankings, the glamour and the spotlight.

But while their authority over the sport may have waned, their self-belief has not. Seeded six and seven as they are, or as world No1 and No2, they stubbornly believe there are no finer exponents of the game.

"I think it doesn't matter for us how the next player's playing, we believe we're the best on the court at that moment," said Venus, who eased to a 6-4, 6-3 win over world No60 Tamarine Tanasugarn yesterday.

"So it doesn't matter who's in the tournament or not in the tournament. It doesn't play a factor in how we feel about ourselves."

Several of the American observers at these championships are eyeing a potential 'summer slam' of a Williams name being etched on the trophies at Wimbledon, the Beijing Olympics and the US Open in September.

"We hope so," said Serena, a 6-4, 6-0 winner over Agnieszka Radwanska. "Right now, I'm focused on my next opponent and Venus is focused on hers. That's the only thing we look forward to next."

Fair enough. So, is it fair to write off the two brave women who are attempting to steer this unerring Williams juggernaut off course? After all, at No5 in the world, Elena Dementieva is the highest seed left in the competition and simple logic would dictate she is favourite.

Furthermore, Zhi Zheng has knocked out four seeds including world No1 Ivanovic on her way to the last four and had too much for Nicole Vaidisova in yesterday's quarter-final.

The issue really comes down to power. Do these two have it within them to not only sustain a barrage of powerful hitting, but then in turn become the aggressor, dictate the play and put the American pair on the back foot?

"Serena, with no doubt, is an outstanding player and so far I haven't found any weak link about her," said 24-year-old Zheng, who could cap her birthday on Saturday in the best way possible with a shot at the title.

"But as a first time in the semi-finals, I would rather now enjoy the game than anything else."

Zheng has something of a bite to her serve, her fastest reaching 106mph against Vaidisova, but at No133 in the world, she has never been beyond the fourth round of a Slam and there have to be questions about whether she can produce her best tennis against such an intimidating opponent on the biggest of stages.

Dementieva has her weakness too. Her notoriously suspect serve will come under tremendous pressure from Venus, who will hit through every return and immediately rush her opponent from the back of the court.

The Russian, perhaps trying the odd mind game or two to distract from the mental frailties in her game, rates Venus the favourite in her particular Williams challenge.

"Venus is the defending champion - it's all pressure on her," she said, having blown a 5-1 lead to wrap up victory over Nadia Petrova in straight sets before eventually coming through in three.

"I really have nothing to lose. All I need is just to have a day off to recover, just to play my game, just to enjoy the moment."

So, Venus, you are favourite for the whole thing according to your next opponent - and, incidentally, with the bookmakers - so, how does that affect your preparation?

"It's nice to be favourite, that's for sure," she said "But I'm gonna go out there and work just as hard as if I was or if I wasn't the favourite."

Of course, Serena is close behind both in the betting and is many people's idea of a champion, so how does she feel about her sister being described as the woman to beat in west London?

After all, conspiracy theorists would suggest that the result of an all-Williams final will be decided over breakfast in their flat on Saturday morning.

"I am going to sabotage her and eat all the breakfast," said Serena. "I'll eat all of the Wheaties so she doesn't have any chance, if we get that far.

"And I would never sit here and say she's the favourite when I am still in the draw - what are you on?" Fighting talk indeed - let battle commence.