WATCH: Andreescu, 18 & No. 152, upsets top seed Wozniacki in Auckland

AUCKLAND, New Zealand (AP) — Overcoming a back injury and a cold, Canadian teenager Bianca Andreescu upset top-seeded Caroline Wozniacki 6-4, 6-4 Thursday and advanced to the quarterfinals of the ASB Classic.

The 18-year-old Andreescu, a qualifier ranked No. 152, has won Australian Open and French Open junior doubles titles and was ranked No. 3 as a junior.

"I can't believe it right now," Andreescu said. "I've always dreamed of playing on this stage against top players and now I'm here I played against one of the best and so I really don't what to say right now."

Andreescu will next face another former No. 1, Venus Williams.

HIGHLIGHTS:

Against Wozniacki, Andreescu needed a medical time out at the start of the second set for her back injury but she still managed to chase down shots and win vital points.

Andreescu was coughing throughout the match and also had to endure a brief rain delay while trailing 4-3 on serve in the second set. She came out and held, broke Wozniacki for a 5-4 lead and then served out the match on her first match point.

"I've actually had this cough for three weeks now so I'm used to it," Andreescu said. "I've also had a couple of back issues the last couple of months but I managed to pull through, I have no idea how. I just fought for every point."

Williams, who beat former No. 1 Victoria Azarenka in the first round, defeated 2017 ASB Classic champion Lauren Davis 6-4, 6-3.

"I think it was even cleaner than the first round," Williams said. "But I'm still searching for perfection and she really, really, really can hit the ball.

"I'm 6-1 and a foot taller than her but she hits it just as hard so I had to be on my toes."

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