Madison Keys has dumped seventh seed Simona Halep out of the Sydney International.
The American, who reached the quarter-finals last year, broke four times on her way to claiming the first set 6-1 in their first-round clash.
She faced only three break points - losing one - despite managing just a 36% success rate on her first serve.
Keys continued to struggle on serve in the second set, but still streaked into a 5-0 lead before Halep mounted a comeback.
However, the 18-year-old closed it out 6-4 and will face the winner of Daniela Hantuchova and Ajla Tomljanovic in the next round.
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