Another telling performance from Serena Williams, who still hasn't lost a set at this year's Australian Open. Next up is 34-year-old Mirjana Lucic-Baroni in the semifinals. Serena leads their head-to-head series 2-0, which isn't all that interesting. But what is interesting: They haven't met since … last century (Wimbledon, 1998, where Serena won 6-3, 6-0).