South Africa's Kevin Anderson has booked his spot in the quarter-finals of the Vienna ATP 500-level event after a solid win over Spain's Pablo Carreno Busta.
Anderson, the world No 111, beat the 15th-ranked Carreno Busta 7-5, 6-1 on Wednesday.
The 2018 Vienna champion will now face either fourth seed Daniil Medvedev or Canada's Vasek Pospisil in the last eight.
In his opening match, Anderson saved three match points before beating Austrian Dennis Novak 6-7 (2/7), 6-4, 7-6 (8/6).
Results from the ATP tournament in Vienna on Wednesday (x denotes seeding):
Stefanos Tsitsipas (GRE x3) bt Jan-Lennard Struff (GER) 6-7 (3/7), 6-3, 6-4
Vasek Pospisil (CAN) bt Felix Auger-Aliassime (CAN) 7-5, 7-5
Daniil Medvedev (RUS x4) bt Jason Jung (TPE) 6-3, 6-1
Jannik Sinner (ITA) bt Casper Ruud (NOR) 7-6 (7/2), 6-3
Novak Djokovic (SRB x1) bt Borna Coric (CRO) 7-6 (13/11), 6-3
Kevin Anderson (RSA) bt Pablo Carreno Busta (ESP) 7-5, 6-1