World No1 Lydia Ko has safely advanced to the second round of match play in the 2012 US Women's Amateur Championship at The Country Club in Ohio.
New Zealander Ko defeated Oregon's Amy Beth Simanton 4 and 3.
The 20-year-old Simanton got off to a fast start with a birdie to win the first hole, but never again led in the match. At the second, Ko pulled all-square with a 1m birdie putt and went 1 up with a 4m putt for birdie at the fourth.
Ko's pars won the sixth and seventh holes and she made a 5m for birdie to win the eighth and go 4 up. After an exchange of holes, Ko went 5 up with a birdie at the 13th and clinched the win on the 15th hole.
Among those advancing with Ko were medallist Hyo-Joo Kim from South Korea, Amy Anderson the 2009 US Girls' Junior champion and a member of the 2012 USA Curtis Cup Team, and Ariya Jutanugarn, 16, of Thailand, who won the 2011 US Girls' Junior.
Match-play rounds continue throughout the week with a 36-hole final scheduled for Sunday.