Top seed Novak Djokovic and defending champion Roger Federer both progressed to the last eight of the Dubai Championships with straight-sets wins.
Djokovic extended his unbeaten run to 15 matches with a 6-1 7-6 (7-4) win over Spain's Roberto Bautista-Agut.
"I played a good match for an hour or so, but then I didn't stay committed to every point," said the Serb.
Federer looked far more confident than he had in his
beating Marcel Granollers 6-3 6-4.
"It's something I have been trying my whole life, to be more aggressive," said Federer, who had to come from a set down to beat wildcard Malek Jaziri in the previous round. "I would like to serve-volley more, but I'm winning so it's OK.
"I was sharper. I had a more clear plan. I knew what I could and couldn't do."
Argentina's Juan Martin del Potro beat India's Somdev Devvarman 6-4 6-4 to remain on course for a semi-final tie with Djokovic, while Tomas Berdych of the Czech Republic beat Tobias Kamke of Germany 7-5 6-1.