Bucharest - Top-seeded Grigor Dimitrov advanced to the final of the Nastase Tiriac Trophy on Saturday when Gael Monfils had to retire with an ankle injury in the first set.
Monfils twisted his right ankle when walking onto the court before the match and had to quit when trailing 5-1 after just 16 minutes of play.
Dimitrov will play defending champion Lukas Rosol in Sunday's final, after the Czech player rallied to beat Robin Haase of the Netherlands 3-6, 6-3, 6-2.
Dimitrov is looking for his third career ATP title but said he was disappointed Monfils wasn't able to continue playing.
The Bulgarian said that "as much as I am happy, it is an undeserved win and unfortunately it had to end that way. I hope he will be OK for the coming weeks."