World number two Caroline Wozniacki survived a scare from Ashleigh Barty on Monday, edging the Australian 6-2 4-6 6-4 to reach the last-16 of the Madrid Open.
Wozniacki found herself on the brink of defeat as she trailed 4-2 in the final set, but the Dane roared back to claim the last four games to seal the victory.
The 22-year-old Barty was ultimately let down by her groundstrokes in crucial stages of decider as she finished with 54 unforced errors for the match.
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Wozniacki will next face former French Open semi-finalist Kiki Bertens, who stunned 15th seed Anastasija Sevastova 6-1 6-4 in the second round.
Former world number one Maria Sharapova's revival on clay is gathering pace as she overcame a tense opening set to beat Romania's Irina-Camelia Begu 7-5 6-1.
The 31-year-old Russian, who entered the tournament on the back of four consecutive defeats, rallied from 3-1 down before snatching the opening set with a ferocious forehand.
With momentum on her side, Sharapova won 20 of the last 22 points to secure a spot in the last-16.
"Although I didn't play at my best level in the first set, I pulled it through," the five-time grand slam champion told a news conference.
"I played some really tough points. I hung in there especially in that final game. Then I really set up a good opportunity for me to step up.
"I thought I did a really good job of that, especially in the last six games. I was very aggressive, played deep, returned a lot better. That will certainly help me moving forward."
Unseeded Sharapova will next face last year's finalist Kristina Mladenovic, who edged China's Zhang Shuai 6-4 4-6 6-3.
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