Dane Holger Rune, the No 4 seed, moved into the quarter-finals of the Swiss Indoors by defeating Swiss wildcard Dominic Stricker 6-3, 7-6 (2) in Basel.
Rune, ranked No 14, will face Belgian lucky loser David Goffin next.
Ahead of his victory, the 21-year-old Dane won against Chilean Nicolas Jarry (6-4, 7-6 (3)).
Stricker, ranked No 258, beat Dutchman Tallon Griekspoor (6-4, 6-4) in the previous round of the Basel tournament.
Basel ATP 500, other second-round results (St. Jakobshalle., hard, EUR 2.385.100, most recent results first):
- Felix Auger-Aliassime vs. Giovanni Mpetshi Perricard
- Denis Shapovalov (WC) beat Roberto Bautista Agut: 6-3, 7-6 (4)
- Ben Shelton (6) beat Stan Wawrinka (WC): 7-6 (2), 7-5
- Arthur Fils (7) beat Pedro Martinez Portero: 7-5, 6-3
- Stefanos Tsitsipas (3) beat Botic van de Zandschulp (Q): 7-6 (3), 7-5
- Andrey Rublev (1) beat Alejandro Tabilo: 7-6 (3), 6-1
- David Goffin beat Ugo Humbert (5): 3-6, 6-1, 7-6 (7)