World number one Novak Djokovic has beaten Russian Karen Khachanov 6-3 7-6 at Dubai Tennis Stadium.
Djokovic will play Czech qualifier Jiri Vesely in the quarter-finals.
Elsewhere in the round-of-16, Russia's second-seeded Andrey Rublev beat Kwon Soon-woo of South Korea in three sets 4-6 6-0 6-3.
Fifth-seeded Pole Hubert Hurkacz defeated Slovakia's Alex Molcan 6-3 6-2.
And Lithuanian Ričardas Berankis triumphed over Alexei Popyrin from Australia 6-4 7-6.
In today's early game on centre court, fourth-seed Jannik Sinner of Italy beat Britain's Andy Murray 7-5 6-2.
And American Mackenzie McDonald won in a 6-4 7-6 tiebreak against Serbia's Filip Krajinovic.
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