Frances Tiafoe paced American compatriot Tommy Paul into the quarter-finals of the ATP event in Kazakhstan on Wednesday with a 7-5,6-3 defeat of Serb second seed Miomir Kecmanovic.
Joining Tiafoe in the last four was seventh-seeded Paul, a winner over Radu Albot 6-4, 6-0.
A third American, Mackenzie McDonald, reached the second round in the capital over local Alexander Bublik 6-3, 6-2.
Tiafoe spent 81 minutes in advancing, losing just five points on his first serve in a dominating performance.
Kecmanovic won his first career title in Kitzbühel in September.
Tiafoe next faces Egor Gerasimov after the Belarus player defeated Czech Jiri Vesely 4-6, 6-3, 6-4 in just under two hours.
The winner managed 14 aces to reach a second quarter-final of the season after Marseille in February before the COVID-19 pandemic began to spread in the West.
Australian fourth seed John Millman posted a 6-3, 6-4 defeat of Spain’s Fernando Verdasco for a last-eight spot and will next play Paul.
Mikhail Kukushkin got a Kazakh win as he beat Argentine Federico Delbonis 6-7(5), 6-3, 6-2; that earned him a second-round match with French top seed Benoit Paire, who benefitted from a first-round bye.