As the peak period of the tennis calendar approaches - with four out of six weeks containing Grand Slam play at the French Open and Wimbledon from late May through early July - much has been written about the men's game of late, with Roger Federer and Rafael Nadal once again being the focus attention. Sports fans - not just tennis afficianados - would welcome another epic duel between the two this year.

But unless one is a passionate tennis fan the women's game generates scant enthusiasm and significantly less media attention. And for good reason: for some time now the top women have been lacking consistency and, more importantly, a compelling rivalry on which to anchor their sport.

Individual sports are far more dependent on rivalries than are team sports. While there are always historic rivalries present in team competition (Yankees-Red Sox, Cowboys-Redskins, Patriots-Colts, Lakers-Celtics, Bruins-Flyers, et.c) and many would argue these sports are better off when those high profile teams are doing well, those sports' success is less contingent on them, as there are always other battles present that suffice most years. There are just simply more of them to go around.

Tennis needs and demands a rivalry for it to sustain and enrich the public's desire to view the action. And for the last several years the women haven't been able to provide them on a regular basis.

But it hasn't always been this way. Far from it in fact. Since the advent of the Open Era in 1968 the women were blessed with tremendous matchups starting with Billie Jean King, Chris Evert and Evonne Goolagong often meeting in major finals. This then bled into the singular and all-time rivalry of Evert and Martina Navratilova, which morphed into a late-stage Martina and a young Steffi Graf. And this string of fantastic competitions concluded with Steffi and Monica Seles conteseting a heated and intense rivalry that ended all too briefly in 1993 when Seles was stabbed in Germany (Graf also had some thrilling matches with Aranxta Sanchez Vicario whose patient game often gave her fits). The women haven't supplied such a rivalry that marries consistency and intensity since then.

Of course there have been extraordinary players, performances and matches among the women over the last decade. One need not look further than the Williams sisters as they've actually provided the only consistency in the sport, however spotty at times it has been. Since 1999 either Venus or Serena have been in a Grand Slam final every year except once (2006). It's amazing to think that they've been a presence in the sport for 14 years now, starting with Venus' stirring run to the U.S. Open final in 1997. The sisters have also participated in arguably the two best matches in recent memory - Venus' victory over Lindsay Davenport in the 2005 Wimbledon final and Serena's victory at Wimbledon last year over Elena Dementiava.

When Venus first came along she and Martina Hingis seemed destined to develop a long and contentious rivalry. But that fizzled rather early as Hingis proved to be more of a bridge between Graf and the new power generation most personified by the Wililams sisters.

Then when Serena came up, it was thought that the two sisters would gift fans an extraordinary run of a dual domination in the sport with thrilling matches along the way. On this they have satisified their part of the bargain - at the start. The siblings have encountered each other across the net eight times in Slam finals, which is one more than Roger Federer and Rafael Nadal. And from the French Open in 2003 through the Australian Open in 2004 the sisters met in four consecutive Grand Slam finals. No other pair of women have accomplished this in the Open Era.

However, within that span of time Serena was clearly the dominant player and won those four finals with only one going the distance. After Venus' second Wimbledon triumph in 2001 she didn't reach the winner's circle at a Slam again until her third victory in London in 2005. So while the two continued to meet often, it was a one-sided rivalry. And a one-sided rivalry is no fun.

Some in the tennis community have criticized the Williams sisters for appearing less than enthusiastic (that's putting it mildly) in the non-Slam events. While this critique may be fair, perhaps it's what has kept them at least intermittently motivated all these years later. It's similar to Andre Agassi as he was often absent, physically and mentally, for prolonged stretches of time but this is what allowed him to last longer in the sport. He remained a threat until 35 years old. So Venus and Serena having many other interests outside the sport has given them a sense of equilibrium and inner direction that often eludes athletes and has let them avoid burnout.

The other rivalry that seemed to be heading toward greatness was that of Serena and Justine Henin - until Henin abruptly left the sport a couple of years ago. But the two never met in a Slam final until this year when Serena won in three sets in Henin's first Slam back after returning to the sport. It's hard to elevate a rivalry to a stellar status unless a championship is on the line, which is why Federer-Nadal is so extraordinary - seven of their eight Slam meetings have been in finals and overall, 16 of their 20 encounters have come in finals. Rare indeed.

And what of Maria Sharapova? The three-time Slam winner has had miserable luck and has been derailed by injuries so often that she's not considered a factor at this time - which is really a shame as her competitive zeal has never been in doubt.

But now that Henin is once again a fixture at tour events perhaps she, along with countrywoman - and mom - Kim Clijsters, who also returned from sudden retirement last year, will give the tour some much needed consistency and drama. We can't expect Serena and Venus to be around forever so it'd be truly rewarding if the next few years are filled with excitement from this group.