Wawrinka defeated Guillermo Garcia-Lopez 6-1, 6-4 by fighting off 10 break points. He was able, however, to finish off three of his own chances and get to his fourth final this year.
Mahut got by Xavier Malisse 6-3, 6-3. Mahut usually survives on the strength of his serve -- he had 11 aces -- but was able to get four breaks against Malisse. That includes going 3-for-3 in break opportunities in the second set.
Saturday's final will be the first ATP meeting between Mahut and Wawrinka.
Mahut, 240th in the rankings, is appearing in his first title match since 2007, when he lost two finals within a month of each other. He's never been in another title match.
Wawrinka, 10th in the world rankings, is 4-8 all-time in finals. He is 1-2 so far in 2013, including a loss at Buenos Aires. He won the early May ATP stop in Portugal but lost in the finals in Madrid a week later.