Swiss teenager Dominic Stricker stunned the second-seeded Hubert Hurkacz 7-6 (5), 7-6 (5) Thursday to reach the quarterfinals of the Stuttgart Open. The 18-year-old Stricker, who is ranked 335th, once again showed his composure in the tiebreakers a day after beating Radu Albot 7-6 (4), 7-6 (5) on his grass-court debut. Stricker hit eight aces and saved five of the six break points he faced against Hurkacz to set up a meeting with Sam Querrey. The American defeated Australian qualifier James Duckworth 6-4, 7-6 (7). Stricker was ranked No. 1,168 at the start of the season but is climbing rapidly. He also reached the quarterfinals on his ATP Tour main draw debut in Geneva three weeks ago.