Australian Open champion Sofia Kenin, defending champion Belinda Bencic and third seed Elina Svitolina made swift exits at the Dubai Duty Free Tennis Championships after they all fell in the first round on Tuesday.
Fifth seed Kenin was eliminated by Kazakh Elena Rybakina, who came back from a set down to win 6-7(2) 6-3 6-3 in exactly two hours.
Rybakina, who was the runner-up at the St Petersburg Open on Sunday and landed in Dubai only the day before, converted four break points and fired 25 winners while Kenin struggled with her service, serving six double faults.
The 20-year-old Rybakina is yet to lose a three-setter this year and this was the seventh time she managed to get over the line in the deciding set.
Meanwhile, Russia's Anastasia Pavlyuchenkova scripted a memorable upset when she came back from a set down to oust Bencic 1-6 6-1 6-1.
Fourth seed Bencic initially reeled off 19 consecutive points in the first set and was five points away from a rare 'golden set' before Pavlyuchenkova got on the scoreboard to avoid further embarrassment.
However, the next two sets were a stark contrast to the first as Pavlyuchenkova turned the tables on the Swiss, taking command of the contest and converting seven break points in all to advance in 90 minutes.
"I just kept on fighting, still trying to hit every ball, trying to be there," Pavlyuchenkova said. "Mentally I was quite positive, just playing point by point.
"Even though it was 5-0 (and) I thought, 'Oh my God, it's embarrassing,' I think it helped me going into the second set because I took that mentality, that mindset of being positive and fighting, trying to do my thing."
Unforced errors and double faults were a constant feature in the opening set and the opening game of the second set for Pavlyuchenkova before she suddenly shifted gears and fired 14 winners to take the second set.
The 28-year-old then took her service game up a few notches to tighten the screws on Bencic and denied the Swiss any hint of a comeback, winning 12 of the last 13 games to book her spot in the last 16.
Svitolina was another who struggled with her serve in Dubai. She won a meagre 49% of her first service points and lasted only 60 minutes in a 6-2 6-1 loss to American qualifier Jennifer Brady after being broken five times.
(Reporting by Rohith Nair in Bengaluru Editing by Christian Radnedge)
(For more sports coverage, visit the ABS-CBN Sports website).