Lulu Sun has knocked out the No 1 seed in her last three tournaments. Photo: Getty Images (file)
The sixth seed defeated the Russian in straight sets to set up a match against Indonesian third seed Janice Tjen.
Sun has now won nine of her last 10 matches and knocked out the No 1 seed in her last three tournaments.
The 24-year-old was able to break Zakharova when she was serving for the first set and never looked back after that.
On the first match point Sun sent a big serve down the middle of the court, with Zakharova's return going long.
Sun's ranking should climb from 124 to around 114 as she edges closer to securing a place in the main draw the Australian Open in January.
If Sun wins the tournament, she may crack the top 100.
