DUBAI, Feb. 25 (Xinhua) -- World number one Novak Djokovic retired from the Dubai Tennis Championships due to eye problem on Thursday.
The Serb withdrew after losing the first set of a quarter-final match against Spain's Feliciano Lopez.
The last time the Serb retired during a match was against Argentina's Juan Martin del Potro in the 2011 Davis Cup.
World number four Stan Wawrinka of Switzerland won Thursday his quarterfinal match against Germany's Kohlschreiber, 7-5, 6-1.
Kohlschreiber, ranked 34, never really challenged Wawrinka as the Swiss scored seven aces during the encounter.
In other matches, Marcos Baghdatis won 7-5, 6-0 against Roberto Bautista Agut from Spain, while Australia's Nick Kyrgios defeated Tomas Berdych from Czech Republic 6-4, 6-4.