Day 9: Djokovic and Serena semifinals-bound, Aslan roars into last four

Novak Djokovic fends off Alex Zverev to reach the semifinals for a ninth time, Serena Williams produces her best match of the tournament against Simona Halep, Naomi Osaka overpowers Hsieh Su-Wei, and Aslan Karatsev becomes the first qualifier in 43 years to reach the last four of a major, on a historic Day 9 of the Australian Open. See omnystudio.com/listener for privacy information. See omnystudio.com/listener for privacy information.