PARIS – As the stars of tennis converged on the French Open and settled with entourages into bio-secured hotels, Daniel Altmaier was already grafting on the clay courts, getting dirty in the dust and picking up clues here, tips there about the surface's quirks as he fought like a man in a hurry through qualifying to reach the main draw.With his largely unknown name now in the main-draw mix with the rich and famous, the 22-year-old German is proving as stubbornly hard to remove as the courts' ochre brick-dust on fresh linen.Sets lost on his way to the fourth round of his debut Grand Slam tournament: Zero.Nerve-testing tiebreakers won: All three.“I keep going,” the 186th-ranked player said Saturday after his latest upset victory, a 6-2, 7-6.