Mika Liu and Rinko Mitsunaga won the inaugural U.S. Women's Amateur Four-Ball title Wednesday at Bandon Dunes, beating fellow teens Hannah O'Sullivan and Robynn Ree 4 and 3.

The 16-year-old Liu, from Beverly Hills, California, and 18-year-old Mitsunaga, from Roswell, Georgia, were 8 under for 15 holes on the Pacific Dunes course. Liu had six birdies in a seven-hole stretch on the front nine, and Mitsunaga holed out for eagle from the fairway on the par-5 12th.

Liu and Mitsunaga won Nos. 6, 7 and 8 with Liu's birdies to open a 3-up lead, Mitsunaga made it 4 up with her eagle on No. 12 and they halved the next three holes with pars to end the match.

O'Sullivan and Ree won the opening hole with a birdie, Liu and Mitsunaga tied it with a birdie on the second and they halved the par-5 third and fourth holes with birdies.

Liu plans to play at Stanford, and Mitsunaga is headed to Georgia.

The 17-year-old O'Sullivan is from Chandler, Arizona, and the 18-year-old Ree is from Redondo Beach, California. They plan to play at Southern California.

O'Sullivan won the Symetra Tour's Gateway Classic in February in Mesa, Arizona, at 16 to become the youngest winner in the history of the professional circuit.

In the morning semifinals, Liu and Mitsunaga beat Alyaa Abdulghany of Newport Beach, California, and Ellen Takada of Irvine, California, 3 and 2, and O'Sullivan and Ree topped Madelein Herr of New Hope, Pennsylvania, and Brynn Walker of St. Davids, Pennsylvania, 3 and 2.