Naomi Osaka received a walkover into the Doha quarter-finals on Wednesday, while Leylah Fernandez knocked out Australian Open runner-up Zheng Qinwen 7-5, 6-3.

Four-time Grand Slam champion Osaka advanced after Ukraine's Lesia Tsurenko, who beat Ons Jabeur in round two, pulled out with an elbow injury.

Osaka will meet another former world number one, Karolina Pliskova, or Czech teenager Linda Noskova for a place in the last four, as the Japanese star continues her comeback from maternity leave.

Chinese fifth seed Zheng let slip a strong position in the opening set where she led 5-3, as Fernandez broke twice in a row and reeled off the final four games.

Fernandez then punished a loose service game from Zheng in the sixth game of the second set before closing out an impressive victory.

"I'm extremely pumped up, I'm super happy with my level. There's still a lot of work to do, but so far so good, so we're just going to keep going," said Fernandez.

World number 38 Fernandez, a former US Open finalist, goes on to meet third seed Elena Rybakina or 16th-seeded American Emma Navarro for a spot in the semi-finals.

Anastasia Pavlyuchenkova also progressed to the last eight with a 7-5, 6-3 win over Wimbledon champion Marketa Vondrousova.

Katerina Siniakova, who took out Coco Gauff in the second round, could not build on Tuesday's success as the Czech lost in straight sets to Danielle Collins.

Top seed Iga Swiatek plays Ekaterina Alexandrova in the last 16 later on Wednesday.