Argentine counter-puncher Diego Schwartzman overcame a sluggish start to book a place in the French Open quarter-finals with a 7-6(9) 6-4 7-5 win over Germany"s Jan-Lennard Struff on Monday. Despite arriving in Paris on a four-match losing streak, Schwartzman feels right at home at the claycourt major and has yet to drop a set in the tournament. "I love this country, I love Paris. I think my best tennis is always here," Schwartzman said in his on-court interview. "It was not a good clay season, but when I came the first day here I was feeling very well again." Schwartzman was uncharacteristically sloppy in the opening exchanges and littered the court with unforced errors, allowing Struff to break twice and take a 5-1 lead in the opening set. But the world number 10 soon found his rhythm thanks to some crafty shot placement and superb defence as he fended off seven set points before taking the first set. Big-serving Struff never quite recovered from that setback and was pushed around the court by a string of pinpoint groundstrokes from Schwartzman, who claimed a crucial break in the 10th game before taking the second set. Struff, ranked 42nd in the world, rallied from 4-0 down in the final set but Schwartzman did not flinch. The Buenos Aires champion broke Struff"s serve for the eighth time in the match with a superb backhand passing shot, sealing victory in just over three hours on Court Suzanne Lenglen. Schwartzman will next face either Italian teenager Jannik Sinner or 13-time champion Rafa Nadal. The 28-year-old has suffered defeats in his previous two Roland Garros meetings with Nadal, including the semi-final last year. "I think at the beginning of every match against Rafa, you have to walk on the court thinking to win the match," Schwartzman said. "If you think much about the four, five hours you are going to play, if you think about everything about Rafa in Roland Garros, he"s very difficult to play. "It"s always a good challenge. I want to be there one more time."