Schwartzman ends Struff run to reach French Open quarter-finals
Schwartzman will face 13-time champion Rafael Nadal or Italian teenager Jannik Sinner for a place in the last four. He was beaten by the Spaniard in last year's semi-finals.
The 28-year-old saved seven set points in the first set as he rallied from a 5-1 deficit against the 42nd-ranked Struff, who had only once before made the fourth round at a major.
Schwartzman let a 4-0 lead slip in the third set but held on to make his fifth Grand Slam quarter-final.