Barry Flatman, Sunday Times Tennis Correspondent in Dubai
At times they confound, on some regrettable occasions they frankly annoy, and with great regularity they frustrate. But where oh where would women's tennis be without the Williams sisters?
When the pair put their mind to it and commit to the task in hand, they can produce a level of tennis which their challengers in the top echelon of the Sony Ericsson WTA Tour can only watch with a mixture of admiration and envy.
There are many who rightly lament the premature retirement of Justin Henin and the protracted absence of injured Maria Sharapova. Yet if one of the sisters decided it was time to hang up her racket for good and the other was forced to spend more than six months away from the game because her body was not up to the rigors of competition, just what would happen to the women's side of the sport - which already suffers regular criticism for not being as enticing as its male counterpart?
Of course Venus and Serena don't play as much as many would like. Without doubt there have been occasions when both seem preoccupied with matters away from the court and they openly admit they require distractions to keep them interested in the sport that so far has amassednthem a combined $45.5million in prize money alone.
Perhaps the other successful semi-finalist, Virginie Razzano of France, the world No58, was wise to insist she was not intending to watch the nineteenth competitive installment of the sister act and was instead heading to the health spa to rejuvenate her body after a far from demanding 6-1,6-2 win over Estonia's Kaia Kanepi.
Comparing that encounter to some of the hardball the Williams played in the final set of their two hour battle was akin to comparing an impromptu kick-around between office workers nipping out for some exercise at lunchtime with the attacking excellence of Manchester United going full tilt.
Of course there were highs and lows in Venus' 6-1,2-6,7-6 victory that gave her the upper hand in the sister act - she has ten wins to Serena's nine. The pair walked out onto court behind tournament referee Alan Mills in a relaxed chatty mood that suggested they were viewing the match as a public practice session rather than a full-blown show-down.
Serena's play during the twenty minute first set suggested she was prepared to give a place in the final to her big sister without any form of fight. She could only win one of the match's first ten points, delivered six double faults and looked totally out of sorts.
This began to seem like a pre-decided tactic as the plot changed in the second set - Venus was unable to play anything other than a subsidiary role. But when the time came to step up in the final set, Venus's weight of shot, her power and her determination were stirring to behold.
"My serve was somewhere off on vacation," bemoaned Serena, who a week ago declared herself insufficiently fit to contest the semi-final in Paris against Elena Dementieva because of an injured right knee. "I am feeling a little beat up right now because I've never played so much tennis as I have in the past few weeks."
Venus, who just three months ago won the end of season Sony Ericsson WTA Tour Championships in nearby Doha, now goes forward to try to win the 40th singles title of her career. It would take a brave man to bet against her taking the spoils.
But as the pair slugged out the concluding tie-break in a crescendo of powerful blows, the mind clicked back just a couple of weeks to the Australian Open final when Serena completely annihilated the player who currently stands second in the world rankings, Dinara Safina.
It was probably best to purge that memory the moment the contest was over; the reputation of women's tennis gained nothing from what was supposed to be a showcase match. This was different - maybe not as intense as last July's Wimbledon final, but the final set was close.
The sentiment merits repeating. Where oh where would women's tennis be without the Williams sisters?