America's Williams sisters can write another chapter in their eventful family history as they attempt to set up their ninth Grand Slam final, eight years after the last, at the Australian Open today. In a plot straight from the 2000s, both sisters have raced into the Melbourne semi-finals without a dropping a set, and they appear equally focused on getting their hands on the title.At least one American is guaranteed to be in Saturday's decider, with Venus confronting confident compatriot Coco Vandeweghe in their last-four clash on Rod Laver Arena. Following them on court will be Serena against fellow former teenage prodigy Mirjana Lucic-Baroni, who is into her first Grand Slam semi-final in 18 years. It has become a tournament of the golden oldies, with Venus 36, Serena 35 and Lucic-Baroni 34.Vandeweghe at 25 is the young pretender. Serena said it was a testament to the Williams' staying power that they were still fighting for titles at their age. Few would have picked a Serena-Venus final as the tournament got underway, but it is now a 50-50 chance. They last met in a major decider at Wimbledon in 2009, which Serena won. The younger Williams has the clear edge, winning six of their eight Grand Slam final encounters stretching back to the US Open in 2001.