German Angelique Kerber turned in her best Dubai Tennis Championships performance by producing a 6-2, 6-3 defeat of Monica Puig on Wednesday.
The victory in 65 minutes moves the top seed a step closer to a return to the WTA number one ranking should she win the title in Saturday's final. That scenario would drop Serena Williams back to second in the table.
Kerber also earned satisfaction in beating the 42nd-ranked Puig after the Puerto Rican won their Olympic gold medal match in Rio last August.
Kerber, whose early season form has been marginal at best, is surprising herself with good play at the Aviation club, where she had never previously reached the quarter-finals.
"I've never played well here; I don't know why, but this year I'm feeling good from the beginning. I was a little bit sick last week. I'm happy I've found my rhythm back.
"I was trying to play my game. I'm really happy about how I played today," Kerber said. "I was really trying to stay focused on every single point and trying to move well, bringing a lot of balls back."
The German will Thursday take on Croatian Ana Konjuh, who beat eighth seed Elena Vesnina 3-6, 6-4, 7-6 (7-4).
Seventh seed Elina Svitolina spent almost two and a half hours in defeating American Christina McHale 4-6, 6-4, 6-3.
Svitolina said she barely came through for the tight win. "I was fighting myself today, I was not there for important points. I didn't do my best, but then I'm really happy that I won.
"This shows I can go through some tough matches even not playing well and then try to find my game," she said. "At the end of third set, I found it. It's positive that I fought to the end and didn't give up."
Lauren Davis advanced over Russian Ekaterina Makarova 4-6, 6-1, 6-3 while Wang Qiang deflated the joy for Kristina Mladenovic 6-1, 6-4 just 24 hours after the French player has upset second seed Karolina Pliskova.
