Dubai - Angelique Kerber and Elina Svitolina will face off in a Dubai Championships semi-final on Friday after both ran down opponents in quick straight-sets wins.
Holder and top seed Svitolina defeated Japan's Naomi Osaka 6-2, 6-4 on Thursday while German sixth seed Kerber won a rematch of the 2016 US Open final, beating Czech Karolina Pliskova 6-4, 6-3.
Kerber improved her record over Pliskova to 7-3 after winning five of their last six matches against her fellow former WTA number one.
Kerber, ranked ninth after a solid start in 2018, claimed her 15th win of the season, pulling her level for the lead on the WTA circuit with number one Caroline Wozniacki.
"I was playing quite good today, serving well was the key for the match," Kerber said.
"She hit the ball really hard, serving good. I was trying to put good returns back, and just play my game.
"I have much more confidence than when I started the year where I actually had no idea where I was, especially after last year.
"I have already so many matches under my belt, so that gives me much more match confidence.
"I'm going out there and just thinking about the next match, the next point - nothing else."
Pliskova was playing her first Dubai quarter-final since finishing runner-up three years ago.
Kerber reached the final four in an hour and a quarter with three breaks of serve without facing a challenge to her own serve.
Svitolina ended a run of two 2016 losses to Osaka, ranked 48th and first Japanese quarter-finalist at the event since 2004.
"I had a couple of tough matches against her. I had to be ready for her to come back," Svitolina said. "I had to be ready for her to raise her level."
Svitolina, looking for her 11th career WTA trophy, was coming off an opening challenge less than 24 hours earlier when she beat Chinese lucky loser Wang Qiang.
The world number four took commanding control of the opening set against Osaka, stamping her authority on the session with a 5-0 lead.
After claiming the first set, Svitolina faded slightly, with Osaka breaking in the second game and reaching a 4-1 lead before slowly being reeled in.
Svitolina broke back for 3-4, added an insurance break for 5-4 and closed out the win on a net cord in her favour on first match point.
"Definitely I'm happy the way I've been handling the pressure and tough moments," she said.
"I had two good matches. I cannot say it was amazing tennis, but when I needed to I was stepping up and playing well.
"I just stayed in the moment, I was fighting, waiting for my opportunity, trying to earn opportunities.
"This was pretty much it - she gave me a chance and I took it. This was the key."