Agnieszka Radwanska crashed out of the Dubai Tennis Championships, suffering a shock 6-4 2-6 6-2 defeat to American teenager Catherine Bellis.
The world No 6 and fourth seed joined world No 3 Karolina Pliskova in crashing out of the tournament early, following a three set defeat to 17-year-old Bellis.
Radwanska, champion in Dubai in 2012, battled back to level the match after losing the opener but Bellis showed remarkable composure to race through the decider and seal the biggest win of her career.
“It’s one of the best feelings in my life, for sure,” said Bellis. “I’m really happy about the outcome tonight.
“It feels really good. I think I’m definitely playing some of my best tennis right now. It’s definitely obviously the biggest win of my career, and probably one of the best days of my life.”
Next up for Bellis is Danish tenth seed Caroline Wozniacki, who overcame treatment on her leg at the start of the third set to defeat Kateryna Bondarenko in three sets after more than two hours.
Five of the world’s top 10 women’s players are in action but only three seeds remain after a week of shock results so far in Dubai.
Pliskova, twice a tournament winner in 2017, was beaten by Kristina Mladenovic on Tuesday while French Open champion Garbine Muguruza and Dominika Cibulkova have also perished early.
Top seed and world No 2 Angelique Kerber remains in the tournament and is chasing the world No 1 ranking that would come with tournament victory.
The German remained on course to reclaim top spot from Serena Williams with a quickfire 6-2 6-3 success over Olympic gold medalist Monica Puig on Wednesday.
Kerber’s victory also provided revenge against Puerto Rica’s Puig, who beat the 29-year-old for Rio gold in August.
Next up for Kerber is Croatian teenager Ana Konjuh, who eliminated eighth seed Elena Vesnina while America’s Lauren Davis, China’s Wang Qiang and Anastasija Sevastova also advanced to the quarter-finals.