Simona Halep eased into the last eight of the Birmingham Classic with a straight-sets win over Harriet Dart.

Home hope Dart was looking for a second successive quarter-final, having beaten Donna Vekic and Camila Giorgi in Nottingham last week en route to a place in the last eight.

However, Halep illustrated the gulf in class between the two in her last-16 clash with Dart, surging to a 6-3 6-2 victory as she prepares to try to regain the Wimbledon title she won in 2019.

The second seed will next face another Briton, Katie Boulter, who beat Caroline Garcia in straight sets. Halep's Romanian compatriot Sorana Cirstea overcame Aleksandra Krunic, while there were also wins for Giorgi, Zhang Shuai and Vekic.

At the German Open, fourth seed Karolina Pliskova needed two hours and 11 minutes to see off former US Open champion Bianca Andreescu.

The Czech came through a marathon third set that went to a tie-break, Pliskova having been a break down at 3-1 in the third, prevailing 6-4 2-6 7-6 (9-7).

Pliskova broke Andreescu to level the decider at 5-5 and then saved two break points in her subsequent service game before converting her third match point in the tie-break.

It marked Pliskova's first complete win over Andreescu, her only previous success coming via retirement at the 2019 WTA Finals.

"Of course Bianca is a super-tough opponent, she can really give you anything," Pliskova said after the match. "Slices, she can play fast, she can serve really well, she can come to the net.

"So I think there was a little bit of everything in this match. I'm super proud that I was able to turn the match around, because I was losing in the third set. I thought she was a little bit better in the second and third sets, but I stayed in there and I fought and I got my chances in the end."

French Open runner-up Coco Gauff had an easier time of things in her opening match in Berlin, defeating Ann Li 6-2 7-6 (7-2).

Maria Sakkari got the better of Daria Saville 6-1 7-5, Daria Kasatkina came back from a set down to knock out Ekaterina Alexandrova 5-7 6-1 6-1 and Aliaksandra Sasnovich saw off Andrea Petkovic 6-4 6-4.