World number two Angelique Kerber was sent home after just one match at the Qatar Total Open on Thursday.
Daria Kasatkina upset the top seed 6-4, 0-6, 6-4 in a touch over two hours on the hardcourts of the Qatari capital.
The Russian battled to a 3-1 lead before serving out the opening set. However, Kerber pulled herself together to blitz the second set in just 28-minutes to set up a decider.
But the German capitulated early on and could not recover from 4-0 down as Kasatkina earned ther second win in as many months over the two-time grand slam winner. Kasatkina defeated Kerber in straight sets in Sydney in January.
— WTA (@WTA) February 16, 2017
"It's my second year on the WTA Tour, so I have to grow up!" laughed the 19-year-old in her on-court interview.
"I am happy that I went through this and I am in the quarters."
Elsewhere, second seed Karolina Pliskova had no problems getting past Caroline Garcia 7-5, 6-4 to reach the last eight while Lauren Davis eased past Elena Vesnina 7-5, 6-2.