Novak Djokovic set up a semi-final meeting with Daniil Medvedev at the Astana Open on Friday, cruising past Karen Khachanov in the last eight.
Djokovic complemented a fine display of serving by converting three of his five break points in a 6-4 6-3 victory, recording his seventh consecutive win following his absence from the US Open.
The 21-time grand slam champion has now reached six semi-finals this year, but saw room for improvement in his performance after beating the world number 18.
"I didn't play as well from the baseline as I did in the first two matches, but still it was enough," Djokovic said. "I managed to produce some good tennis when it was most needed in both sets."
Looking ahead to his final-four match, the Serb added: "I always expect highs from myself. Hopefully I can elevate still the level of my game for tomorrow, because it's going to be needed."
Djokovic will face an 11th tour-level meeting with Medvedev in the next round after his fellow former world number one recorded a dominant 6-1 6-1 win over Roberto Bautista Agut.
On the other side of the draw, third seed Stefanos Tsitsipas beat Hubert Hurkacz 7-6 (10-8) 6-3, and will now face Andrey Rublev after he eased to a 6-1 6-2 win over Adrian Mannarino.
At the Japan Open, a knee injury forced Wimbledon runner-up Nick Kyrgios to withdraw from his meeting with Taylor Fritz, with the American set to take on Denis Shapovalov in the semi-finals.
Seventh seed Shapovalov saw off Borna Coric 6-4 6-3 to reach the final four, while fourth seed Frances Tiafoe advanced with a 6-0 6-4 win against Miomir Kecmanovic.
South Korea's Kwon Soon-woo claimed the final place in the semi-finals in Tokyo, beating Spain's Pedro Martinez 6-3 6-0