The U.S. got a scare in South Korea's half of the 10th, when Byung Ho Park -- whom the Twins bid $12.85 million to negotiate with -- walked to load the bases. But the Americans induced a groundout to end the game.
Starter Zeke Spruill threw six scoreless innings, giving up three hits and walking two, while striking out seven.
Team USA faces the Netherlands in the quarterfinals, while South Korea faces Cuba.
Mexico 9, Dominican Republic 6
Mexico advanced to the quarterfinals, thanks to a big day by Kevin Medrano, who went 3-for-5.
Puerto Rico 7, Chinese Taipei 4 (12 innings)
Aldo Mendez hit a walk-off grand slam to give Puerto Rico the victory and a spot in the quarterfinals.
The score was tied at 1 after 10 innings. Both teams scored two runs in the 11th and Chinese Taipei took a one-run lead in the top of the 12th before Mendez's heroics.
Cuba 2, Italy 1
Cuba advanced to the quarterfinals, thanks to Alfredo Despaigne's go-ahead single in the seventh.
Canada 3, Netherlands 1
Chris Leroux threw seven strong innings and Jordan Lennerton hit a two-out, two-run double in the sixth to lead Canada to victory. Sean Jamieson added a solo homer for the Canadians.
Japan 6, Venezuela 5
Akira Nakamura hit a walk-off single in the ninth to keep Japan undefeated. Nakamura, a power-hitting first baseman who launched 30 homers in 2015, has 13 RBIs so far in the tournament.
Sho Nakata added a two-run double.
Mexico vs. Canada
South Korea vs. Cuba
Netherlands vs. U.S.
Puerto Rico vs. Japan
Cash Kruth is a reporter for MLB.com. Follow him on Twitter at @cashkruth. This story was not subject to the approval of Major League Baseball or its clubs.