Ons Jabeur built on her encouraging early season form by clinching her biggest win for many months as she upset the No 7 seed Zheng Qinwen at the Qatar Open on Tuesday night.
The former world No 2 has showed signs of getting back to her best during the Middle East swing, defeating Jelena Ostapenko and pushing Elena Rybakina to a final set breaker in Abu Dhabi last week.
The Tunisian again looked in good touch as she landed her first victory over a top-10 player since last April, proving a worthy winner 6-4, 6-2 over Zheng in Doha.
Jabeur warmed to the task as the match progressed – winning 11 of the final 14 games – and then admitted that the confidence was flowing as she soaked up the plaudits from the crowd.
“There was a lot of believing in myself in preparing for this match,” said Jabeur, who will next face 2020 Australian Open champion Sofia Kenin in the last 16 on Wednesday.
“That definitely helped. I tried to stay as focused as I can. It's very tough to play against her; she's a champion. So, I'm very pleased with this win, and I hope I can keep performing even better for the future.”
Meanwhile, Coco Gauff suffered a surprise early exit with a straight-sets defeat to Ukraine's Marta Kostyuk.
Former US Open champion Gauff blew a healthy advantage in the second set as Kostyuk sealed a 6-2, 7-5 victory and a third-round meeting with the winner of an all-Polish tie between Magda Linette and Magdalena Frech.
“Coco is an incredible fighter,” Kostyuk said. “We always have incredible matches. I tried to stick to what I had to do.”
Gauff, playing for the first time since a quarter-final loss to Paula Badosa at the Australian Open on January 21, served seven double-faults and made 39 unforced errors in an erratic display.
The American made a terrible start, slipping 4-1 behind after dropping her serve twice. Gauff was broken again in the eighth game as Kostyuk secured the first set in just half an hour.
The world No 3 hit back with a break en route to a 4-2 lead in the second set as she started to find her rhythm.
But Kostyuk battled back, taking advantage of an error-strewn Gauff performance which ended when she served two double-faults to be broken for the fifth time.
“The double-faults made it easier for me … I'm very happy that it ended in two sets,” Kostyuk said.
Rybakina, who lost to eventual winner Belinda Bencic in the Abu Dhabi semi-finals last week, saw off Payton Stearns in her opening match.
The fifth seed cruised to a 6-2, 6-4 win despite a late wobble to set up a third-round tie against Slovakia's Rebecca Sramkova who beat Russian teenager Mirra Andreeva 3-6, 6-3, 7-5.
Rybakina led 5-0 in the second set but missed three match points to take it 6-0 and then briefly fell apart as Stearns dragged the set back on serve.
The former Wimbledon champion belatedly got over the line on her fifth match point.
Jasmine Paolini, last year's French Open and Wimbledon runner-up, also made a winning start to her campaign with a 6-3, 6-4 victory against Caroline Garcia in the second round.
Czech youngster Linda Noskova earned a last-16 tie against three-time defending champion Iga Swiatek with a 6-2, 6-3 win over Kazakhstan's Yulia Putintseva.
