Clint Dempsey was among coach Jurgen Klinsmann's starters again, while DeAndre Yedlin came on as a second-half sub.
It's great to advance out of the group, even though we thought we would," Dempsey told ESPN after the match.
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The US advances to face Belgium -- the winner of Group H -- at 1 p.m. Tuesday in Salvador.
Before the start of group play, Sounders FC coach Sigi Schmid had tabbed Belgium as one of his sleeper teams for this World Cup:
"Belgium has a great young team," he said. "They might be a shade too young, but they’re all sort of together from Hazard and Vincent Kompany and Witsel and some of the players that they have – Courtois in goal. They’ve got a really, really strong young nucleus."
Here's a report from U.S. Soccer:
Just about four hours after earning passage to the Round of 16 at the 2014 FIFA World Cup, the U.S. Men's National Team learned its opponent for the knockout round game and it will be Group H winner Belgium.
Belgium, which rested a few key players in its final Group H match in Sao Paulo, defeated the Korea Republic 1-0 despite losing Steven Defour to a red card at the end of the first half. The lone goal came in the 78th minute as Jan Vertonghen finished a rebound off the Korean goalkeeper.
The result gave Belgium the full nine points from three wins to take first in the group ahead of second-place Algeria, which came from behind to draw 1-1 with Russia in Curitiba. The Fennec Foxes finished with four points and will meet Group G winner Germany in the Round of 16.
The USA is 1-4-0 all-time vs. Belgium, but the teams are not total strangers in World Cup play. The first meeting between the countries came at the 1930 FIFA World Cup in Montevideo, Uruguay, a 3-0 victory for the Americans in the first-ever World Cup match for the United States.
The most recent meeting between the U.S. and Belgium was a 4-2 loss on May 29, 2013, in Cleveland, Ohio. Geoff Cameron and Clint Dempsey both scored in that game. Belgium is 11th in the last FIFA World Rankings and the USA is 13 th.
For full standings and results, visit ussoccer.com's 2014 FIFA World Cup homepage.