Defending champion Roberto Bautista Agut was dumped out of the Dubai Tennis Championships by Nikoloz Basilashvili and Kei Nishikori suffered a surprise defeat, but Roger Federer moved into the quarter-finals on Wednesday.
Basilashvili will face Borna Coric - who defeated Tomas Berdych - in the last eight after coming from a set down to beat Spaniard Bautista Agut 6-7 (2-7) 6-4 6-3.
The unseeded Georgian blasted down 19 aces and won 81 per cent of points on his first serve, with four breaks of serve seeing him through.
Nishikori suffered only his third defeat of the season as world number 77 Hubert Hurkacz consigned him to a 7-5 5-7 6-2 loss.
The Polish outsider's victory was his first against a top-10 opponent and he did it the hard way, losing the second set after levelling from 4-0 down before dominating the decider.
Federer stayed in the hunt for his 100th ATP singles title, Fernando Verdasco taking the 20-time grand slam champion to three sets for the second time this week before suffering a 6-3 3-6 6-3 loss.
The legendary second seed - who has won all seven of his matches against Verdasco - will now face Hungary's Marton Fucsovics, a 6-4 6-2 winner against Jan-Lennard Struff, following his 50th victory in Dubai.
Stefanos Tsitsipas and Gael Monfils - both eyeing back-to-back titles - advanced at the expense of Egor Gerasimov and Marcos Baghdatis respectively.