The wild card Gea won the first set thanks to a lost serve from Mannarino, but Mannarino was able to win the match in just more than 2 1/2 hours, 5-7, 6-4, 6-4. Mannarino was one of two Frenchmen to come away victorious on Friday, as qualifier Titouan Droguet's 21 aces lifted him to a convincing victory over fourth-seeded Tallon Griekspoor of the Netherlands, 7-6(5), 7-6(1).
Top-seeded Felix Auger-Aliassime of Canada smashed 12 aces to come away with a 6-4, 6-2 victory over his French opponent Arthur Fils.
American qualifier Martin Damm defeated Italy's Luca Nardi in a 6-3, 7-6(8) battle and will face Mannarino in the semifinals on Saturday. Auger-Aliassime will face Droguet immediately after.