Casie Cathrea, Karen Chung and Esther Lee each won two team matches Monday in the Junior Ryder Cup to help the United States take a 6 1/2-4 1/2 lead over Europe at Olympia Fields.
The two-day event will conclude Tuesday with 12 singles matches. The United States won in 2008 and 2010 to level the series 3-3-1.
''Any time you come out of the first day with the lead, it's very good,'' U.S. captain Roger Warren said. ''We still need to finish well tomorrow morning and you never know what can happen in singles.''
Cathrea and Samantha Wagner beat Bronte Law and Quirine Eijkenboom 3 and 2 in the morning foursomes, and Cathrea and Cameron Champ edged Law and Toby Tree 1 up in the mixed fourballs.
''We lost a few holes in a row a few times today but we didn't get down and kept each other up all day,'' the 16-year-old Cathrea said after the morning match. ''We played well as a team and it feels great to get a point for the United States.''
Chung and Casey Danielsonbeat Harang Lee and Covadonga Sanjuan 2 and 1 in foursomes. Chung then teamed with Robby Shelton to top Dominic Foos and Covadonga Sanjuan 3 and 2 in fourballs.
Lee and Alison Lee edged Linnea Strom and Emily Pedersen 1 up in foursomes, and Esther Lee and Jim Liu routed Strom and Victor Tarnstrom 6 and 5 in fourballs.
Alison Lee also was in position to earn a second point in a match that was suspended because of darkness. She and Gavin Hall led Eijkenboom and Matthias Schwab 1 up through 16 holes.
Italy's Renato Paratore was the only European player to win two matches. Paratore and Tarnstrom beat Hall and Liu 3 and 2 in foursomes, and Paratore and Harang Lee topped Danielson and Scottie Scheffler 5 and 3 in fourballs.
''There are still a lot of points to play for tomorrow,'' European captain Stuart Wilson said. ''My players will have no problem getting motivated for tomorrow.''
Morning played was delayed 90 minutes because of frost.