South Africa's Lloyd Harris has reached the quarter-finals of the ATP 250-level event in Cologne, Germany after a win over American Steve Johnson.
Harris, the world No 92, edged the 68th-ranked Johnson in two tight sets, 7-6 (7/5), 7-6 (7/2), to advance to his second ATP Tour quarter-final of the year.
He fired 12 aces past his more experienced opponent.
The 23-year-old South African's best performance this year was reaching the final of the Adelaide ATP event in January.
Harris, who had to qualify for the indoor hardcourt event, has a breather on Thursday and could come up against top-seed and local favourite Alexander Zverev on Friday.
Zverev, the world No 7 and recent US Open finalist, tackles Spanish veteran Fernando Verdasco on Thursday.
Meanwhile in the doubles, South Africa's Raven Klaasen and his Austrian partner Oliver Marach will face Verdasco and countryman Alejandro Davidovich Fokina in the quarter-finals on Thursday.
- Compiled by Herman Mostert