Polish qualifier Hubert Hurkacz stunned top seed Kei Nishikori 7-5 5-7 6-2 to reach the quarter-finals of the Dubai Duty Free Tennis Championships on Wednesday.
Hurkacz converted six out of seven break points to beat his Japanese opponent in a little over two hours. The world number 77 faces Stefanos Tsitsipas or Egor Gerasimov next.
World number 113 Ricardas Berankis, who stunned eighth seed Daniil Medvedev on Tuesday, continued his fine form with a 6-4 6-1 victory over American Denis Kudla.
The Lithuanian qualifier will face Gael Monfils or Marcos Baghdatis in the last eight.
Nishikori crashes to qualifier Hurkacz in Dubai second round