Serena has the habit of a sister superior
A huge advertising billboard alongside the Long Island expressway, which runs out of Manhattan towards Queens and Flushing Meadows, the home of the US Open, proclaims: "New York is getting stronger everyday." For New York, read Serena Williams. While the four men's grand slam titles have been won by different players this year, Serena has bagged the last three on the women's side, and might have won the lot had she not been injured before the Australian Open.
"Everyone has their year, and this has been her year," said her older sister Venus who, as in the French Open and Wimbledon finals, came off second best. "I'm proud of her," she said on court, a few minutes after Serena had mauled her 6-4, 6-3. It was not the reaction any other defeated grand slam champion might have made, and could be regarded as the antithesis of sporting rivalry. But sustained competition at this level between siblings is unique, and the critical parameters remain largely undefined.
Oracene, their mother, was impassive at the end, while their father, Richard, walked away during the second set. "I'm as nervous as hell," he said. " I'm getting out of here right now." It was obvious to him that Venus was struggling and that, as he had predicted from the outset of their tennis careers, Serena would become - and has become - the better player.
The fact that this was the second successive slam that Serena has not lost a single set underlined her dominance. Whereas Venus had difficulties against both her fellow American Chanda Rubin in the fourth round and France's Amélie Mauresmo in the semi-finals, Serena sailed through from start to finish, save for a temporary glitch in the second set of her semi-final against Lindsay Davenport, and that was quickly rectified.
Inevitably Serena's dominance has highlighted Venus's weaknesses, notably the vulnerability of her serve. At Roland Garros this year Venus was broken eight times out of 11 by Serena.
On Saturday night she lost her serve five times out of 10. The first serve can be devastating, as she proved time and again against Mauresmo, but the second is comparatively weak.
Such is the all-round excellence of the rest of Venus's game that few opponents can take advantage. Serena, on the other hand, matches power with even greater power and simply crushes anything short. Venus had to save four break points in her opening service game,and the strain of trying to hold thereafter resulted in a total of 10 double faults, the last presenting Serena with her third and final match point.
Venus has always thrown her head sharply to the left when serving, a fault that has never been rectified. In comparison Serena's serve is classically orthodox and rarely fragments under pressure. Not that she is often pressed. Venus twice managed it, but on the second occasion in the second set, with Serena leading 4-1, there was a distinct element of the younger sister easing off the accelerator just a touch.
A year ago, in the first of their four meetings in slam finals, Venus won the tamest of matches 6-2, 6-4, thereby claiming her second successive US Open title, and her fourth slam, including two Wimbledon victories. This year's all-Williams French Open final was another insipid affair, but Saturday's final, together with Wimbledon, have been altogether more competitive, while at the same time emphasising the individuality of the two sisters.
Here in New York it was ice and fire. Venus displayed virtually no emotion until her final forehand faded into the net,and she smiled broadly at her sister. Serena was all attitude, talking to herself between points, whooping at her winners, and calling balls out, just in case the lines judges or umpire were in any doubt. This latter trait frequently annoys her opponents, and some might have been pleased to note Venus was not spared.
Between them the sisters have now won eight of the last 13 slam titles, stretching back to the 1999 US Open when Serena defeated Switzerland's Martina Hingis. The one title to elude both is the Australian Open and victory next year for Serena would complete the non-calendar grand slam - or "Serena's slam" as she referred to it last Saturday night.
It is currently impossible to see anything, other than Venus or injury, stopping her. There was a time last year, with Venus dominant, when Serena appeared to be drifting, and there were even suggestions she might be disenchanted with tennis. Paradoxically Richard Williams, always the loose canon, called for Venus to turn her back on tennis earlier this year and get a real job.
Given Serena's ever increasing authority, it may be that Venus lays down her rackets first, but their tennis careers have been so intertwined and inter-dependent that it is hard to imagine one carrying on without the other. Which leaves the rest of women's tennis desperately struggling to catch up. "I never want to see Venus lose," said Serena after her fourth consecutive win over her. With a $490,000 (£315,000) cheque in one sister's handbag, and $450,000 in the other, it seems neither of the Williamses can lose.