Wimbledon 2008: Jankovic defeat opens draw up for Williams sisters

With each passing day at SW19, a Williams v Williams final looks like more and more of an inevitability. After Jelena Jankovic's 6-3, 6-2 defeat to the world No60 Tamarine Tanasugarn this afternoon, the women's draw at Wimbledon has now lost all of its top three seeds before the quarter-final stage for the first time since seeding was introduced. Serena and Venus, meanwhile, won their fourth-round matches today with consummate ease.

"I love having [Serena] here and I'm always sad when she leaves and she's gone," said Venus after her win over Bethanie Mattek. "But I realise that nothing is a given. If it was, then every single seed would be lined up ready to play each other."

The fifth seed, Elena Dementieva, remains in Venus's side of the draw, while Serena is likely to face the fourth seed, Svetlana Kuznetsova, in the quarter-finals, yet it would take a brave soul to bet against them. Only once since the turn of the century has neither sister managed to reach the final here and, despite some slow starts last week, both are yet to drop a set so far at this year's Championships.

Perhaps more poignant still, however, is the simple fact that they are both fit and healthy. The top seed Ana Ivanovic looked tired in her third round defeat to Zheng Jie, while the second seed Maria Sharapova was clearly hampered by her chronic shoulder trouble. Jankovic pulled out of a scheduled warm-up event in Birmingham to give herself the best chance of being fit here, yet after jarring her knee on Saturday she received treatment throughout today's match.

"When you're not 100% healthy, it's very hard especially on a grass court, when you have to really move well and you have to be behind the ball," lamented Jankovic, though Tanasugarn also required lengthy treatment for a lower back complaint during the second set. "I have a meniscus tear or something. You can ask the doctors, I'm really not sure."

The WTA season will be shortened from 2009 and player burnout remains a hot topic, yet the Williams sisters have avoided such problems by taking control of their careers. They have come in for plenty of criticism down the years for allowing outside interests and celebrity status to detract from their tennis careers, yet their long-term strategy looks increasingly like a smart one.

Serena Williams averaged just nine tournaments a year, and Venus 10.5, between 2003 and 2007, according to a recent piece in USA Today, while most top pros average 15 or more a year. Such a reduced workload may have kept them from returning to the very top of the world rankings, but as Venus happily points out, she is now 28 and – unlike many of her peers - still enjoying her tennis.

"I just love playing here, I love it. It's what I like best," she insisted when one journalist asked why she seems to manage her game better at Wimbledon. The contrast with Jankovic's slumped shoulders and visible wince as she settled into her chair in the press interview room was a stark one. The family resemblance as Serena waved triumphantly to the crowd on Court Two was all too clear.