Monaco beat American qualifier Michael Russell in three sets 5-7 6-1 6-4 and will play his 13th ATP final.
The first set was decided in the 12th game as Russell manage to break the Argentine to go one set up.
Monaco came storming back in the second set and breaking his opponent three times, he forced a decider.
In the third set, Russell couldn’t hold his serve in the crucial 10th game as he made a couple of unforced errors and the Argentine took the chance and closed out the match.
The no.4 seed Monaco will play American John Isner in Sunday’s final.
Second seed Isner overcame the Spanish wild card holder Feliciano Lopez in three hard fought sets 6-7 (5) 7-6 (4) 6-3.
After the first two sets were both decided in a tiebreak and split evenly, Isner was the first one to break his opponent in the third set and take a 4-2 lead. He then served it out to give himself a chance to claim his first career clay court title.
This will be the second final for Isner this year after Federer defeated him in the Indian Wells Masters to capture the trophy.