Tennis/ Australian Open:Larry Scott, the chief executive of the women's tour, is a man of considerable experience and tennis wisdom: "There's no substitute for winning a lot of matches. I've rarely seen a player come back from an extended injury and perform the way he or she did before. The game moves on."

Scott said this in 2004. The next year, Venus Williams won Wimbledon for the third time with minimal preparation, and on Saturday her younger sister, Serena, won her third Australian Open title in only her sixth tournament of any kind since September 2005. The Williams sisters make fools of everybody.

And long may they continue to do so, would be the cry of many. They are comets of the tennis world these days, blazing into view from time to time and then disappearing, dazzling but rarely inconsequential. Just when the received wisdom, like Scott's three years ago, is that the sisters are not taking tennis seriously, or that their injuries are career-threatening, they re-emerge to turn the form and values of their sport upside down.

"I am what I am," said Serena after beating Maria Sharapova 6-1, 6-2, referring to both her size and her quite astonishing ability. Sinatra may have warbled My Way to the point of tedium. The Williams have lived the song.

There really is little point being critical of the way they choose to flit in and out of tennis, no matter how much it causes Scott and the WTA to gnash their teeth and ponder roadmaps of the future with sinking stomachs.

Whatever is proposed in the way of mandatory tournaments and minimum commitments, Venus and Serena will drive a coach and pair through it, just as Pete Sampras and Andre Agassi always did on the men's tour. And Scott and his cohorts are powerless to prevent it because the Williamses generate huge amounts of money and there are no other American women on the circuit worth a row of tennis balls.

Just as Venus took Sharapova, the then reigning champion, out in the semi-finals of the 2005 Wimbledon with a display of quite ferocious hitting, so Serena disposed of the US-based Russian in brutal fashion. Sharapova, the nominal world number one and schoolyard bully against most other women, was reduced to a quivering wreck.

When she won her second slam title in New York last year there were intimations of maturity and variations, but faced with Serena's cudgel she reverted to type. There were no slices, no drop-shots, few angles, and if she did not go down with a whimper the banshee wails were of no consequence or help.

The Williamses, when they put their minds to it, still play power tennis better than anybody else, and Serena, for whom this was her eighth slam title, the best of all. But the chronic lack of variety in the women's game makes for tedious watching.

One longs for somebody with the brain, variety of shots and anticipation of Martina Hingis who is also physically strong enough to withstand and counter the huge hitters. But to walk around the outside courts during the final week and watch the junior girls did nothing for the spirit of optimism. Here were youngsters welting the ball at one another with no thought of guile or subtlety. It was depressing.

"Maybe in a year or two the women's game will move a level up and we will see them mixing it up," said the four-times slam champion Jim Courier, who was not noted for the subtlety of his own tennis but who is a perspicacious observer of the game.

Maybe. But this was a poor tournament for the women, not helped by Justine Henin-Hardenne's absence and Amelie Mauresmo's early exit. And so it was, underprepared and less than fully fit, that Serena Williams stole the day, albeit that her success underlined the lack of quality in the women's top 20 and the propensity of most in the top 10 to choke when the slam pressure is on.

The men's game has the quality but, with Roger Federer in his pomp, generally lacks drama. The women's game is short on quality but makes up for it with soap-opera dramatics. Serena believes she and Venus will be competing for more major titles this year. Maybe they will, maybe they won't; as always, it is impossible to know with any degree of certainty.

"Serena Williams - yeah, she's back. And this time to stay," she said. We shall see, but, whatever the future holds, Serena's place in tennis history is assured, as is that of her sister.

And deservedly so.

• Guardian Service