World number four Daniil Medvedev refused to continue his match against Serbia's Novak Djokovic after an injury in the second set of the semifinals of the ATP 500 tournament in Astana, Kazakhstan.
The Russian won the first set 6-4, while the second set went 7-6 (8-6) to the Serbian.
In the final of the tournament Djokovic will play against Greek tennis player Stefanos Tsitsipas.