PARIS — Saturday morning at the French Open, Zachary Svajda spent three hours and three minutes serving, sliding and scrambling across the red clay of Roland Garros. The 23-year-old American, who is world No. 85, went up two sets to love on his least-favorite tennis surface against No. 26 Francisco Cerúndolo, a clay-court specialist suddenly blessed with an opportunity to go deep, after Novak Djokovic and Jannik Sinner both went out early.