Seventh seed Andrey Rublev will play Canada's Felix Auger-Aliassime in the final of the Madrid Open.
The Russian beat Taylor Fritz of the United States 6-4 6-3 to reach his second final of the year.
He will face world number 35 Auger-Aliassime after 30th seed Jiri Lehecka was forced to retire midway through the first set of the second semi-final.
A lower back injury led to Lehecka going down in a heap during the seventh game, with the score at 3-3, and the Czech was unable to continue.
It is the third time in the tournament that Auger-Aliassime has advanced as a result of an injury to his opponent.