Over a decade ago, finals between Serena and Venus Williams were commonplace at the highest level of the WTA.  The sisters have met far less often in recent years as they have aged, but they stand one win apiece from turning back the clock in Dubai with another family final.  

This was hardly a foregone conclusion entering the tournament, which featured seven of the top 10 women.  (Venus, a former champion in Dubai, needed a wildcard to receive direct entry.)  Nor was it a foregone conclusion entering the quarterfinals, when each sister faced an opponent who had troubled her chronicallly before.  World No. 7 Jelena Jankovic and US Open semifinalist Flavia Pennetta looked ready to pose stern tests for Serena and Venus, respectively.

Another former No. 1, Jankovic had won only four of 12 previous matches from Serena but had troubled her consistently on all surfaces except grass.  She won sets from the 17-time major chamipion last season on the green clay of Charleston and the indoor hard court of the year-end championships in Istanbul.  With Serena rusty in her return from a back injury, it seemed logical to expect another difficult encounter that would test her consistency.  But this belief proved unfounded, for Serena cruised through in 76 minutes with a much more impressive effort than in her Dubai opener.  Repeating the 6-2 6-2 scoreline of her victory over Jankovic in Beijing last fall, the world No. 1 landed over 70% of her first serves in a comprehensive victory.

Serena's last pre-final obstacle comes from intriguing Frenchwoman Alize Cornet.  A former prodigy who never quite broke through, Cornet has enjoyed a modest revival in recent months.  She reached a Premier-level semifinal at an indoor tournament in Paris this year, and she defeated two top-20 opponents in Kirsten Flipkens and Carla Suarez Navarro in her last two matches.  Still, the world No. 26 will enter her semifinal with Serena as a massive underdog  They have met only once in the last six years, a convincing victory for Serena in Brisbane 13 months ago.  The gulf that yawns between the quality of their serves should place Cornet under much more pressure in her service games.  Often mentally fragile, the Frenchwoman will struggle to maintain her belief under that pressure.

More daunting is the task that lies ahead of Serena's older sister.  Seeking her second final of 2014, Venus must face world No. 11 Caroline Wozniacki„ another former No. 1 famous for extending rallies and testing the limits of an opponent's consistency.  Wozniacki has not produced her best tennis for most of the last two years, but her playing style seems ideally suited to challenge someone like Venus who suffers from Sjogren's disease.  This debilitative condition complicates her efforts to stay fresh throughout the arduous week of a tournament.  Since announcing her diagnosis, Venus often has recorded impressive victories early in the week, only to dip sharply in energy when the later rounds arrive.

But the elder Williams has not lacked impressive victories to this stage, following a rout of former No. 1 Ana Ivanovic with a straightforward victory over Flavia Pennetta.  Venus had lost four of her previous seven matches against the Italian veteran, and Pennetta earned plenty of opportunities today.  Saving 11 of the 15 break points that she faced in two sets, Venus delivered eight aces and raised her first-serve percentage dramatically from the Ivanovic victory.  Despite the less overwhelming scoreline, then, this victory arguably was more notable than the Ivanovic win because of her history against Pennetta and her superior serving statistics.  Venus will need a similarly formidable serving effort to gain the upper hand early in points against Wozniacki, who should hold the edge in longer rallies.

Serena and Venus shared a court earlier this week in Dubai when they played a doubles match, falling to second seeds Ekaterina Makarova and Elena Vesnina.  They might share a court in Dubai again on Saturday if their encouraging form continues on Friday.