DOHA (AFP) – Naomi Osaka battled into the last 16 of the Qatar Open on Tuesday but Coco Gauff and Ons Jabeur crashed to surprise second-round exits with straight-sets defeats.
Four-time Grand Slam champion Osaka brushed past Croatia's Petra Martic 6-3, 7-6 (11/9), continuing a comeback from maternity leave after giving birth to her daughter in July.
Osaka grasped control with a break in the fourth game of the opening set. She broke twice more in the second set -- either side of dropping her own serve -- only to blow a chance to close out the match at 5-4.
Martic threatened to force a third set as she won the first four points of the tie-break, but Osaka then saved four set points before her opponent double-faulted down match point.
World number three Gauff lost 6-2, 6-4 to Katerina Siniakova in her opening match, marking the first time she has failed to reach the quarter-finals of a tournament since Wimbledon last year.
US Open champion Gauff dropped serve six times in an error-strewn display, blowing a 4-0 lead in the second set.
Siniakova will face Danielle Collins in the last 16.
Fourth seed Jabeur slumped to a 6-3, 6-2 loss to Ukraine's Lesia Tsurenko, continuing a difficult start to the year for the Tunisian.
Earlier on Tuesday, Australian Open runner-up Zheng Qinwen battled to victory in her first match since losing the Melbourne final to Aryna Sabalenka, beating Magda Linette 6-2, 2-6, 6-3.