SALVADOR, Brazil (AP) For a full 90 minutes, Belgium's almost relentless attack added up to nothing in the face of Tim Howard.
Only in extra time was the superb United States goalkeeper finally beaten.
Kevin De Bruyne turned Howard's heroic night into defeat on Tuesday when he scored an extra-time goal and then set up Romelu Lukaku for another to give Belgium a 2-1 victory over the Americans. Their reward is a quarterfinal match against Lionel Messi and his Argentina teammates on Saturday in Brasilia.
''For my heart, please don't give me too many games like this,'' Belgium coach Marc Wilmots said. ''He (Howard) was in a state of grace.''
Belgium's unyielding attacks for the full 90 minutes of regulation time only highlighted the great performance of the 35-year-old Howard, but the goalkeeper's teammates finally wilted in the evening heat once extra time came.
''They were all on their limit,'' United States coach Jurgen Klinsmann said. ''(Howard) had an absolutely amazing match.''
Three minutes into the extra period, Lukaku found space on the right and passed into the center. At first, the ball was poked out before De Bruyne gained possession. Belgium's creative genius still had the energy for a sharp turn and his low shot finally missed the yellow foot of Howard and settled inside the post.
Realizing he had finally been beaten, Howard fell back on the grass almost in slow-motion, arms and legs outstretched and eyes staring up into the darkness over the Arena Fonte Nova. The best man of the match turned out to be on the losing side.
''The levee is going to break at some point,'' said Howard, who plays for Everton in the Premier League.
In the 105th minute, Belgium looked like it had put the game away. De Bruyne launched Lukaku into open space on the left and the Everton striker beat his club teammate with a drive to the near post.
It wasn't over on a sticky, anxiety-ridden night, however. The Americans got late hope when Julian Green pulled one back in the 107th minute with a perfect volley on the turn that Thibaut Courtois could only touch before he saw it fly into his net.
Suddenly, Klinsmann started wildly shouting with flailing arms ''Come on, come on,'' and there was a new team on the field.
Now, it was the Belgium's turn to be caught flat-footed.
With six minutes to go, the Americans almost got the equalizer. A free kick move set Clint Dempsey free in the center with only Courtois to beat. But the Belgium keeper proved he is one of the world's best by spreading his giant body to smother the shot.
''The second extra time was a total turnaround. Suddenly, they had all the energy,'' De Bruyne said.
With waves of chants of ''USA, USA'' echoing around the 48,000-seat stadium, the reinvigorated Americans kept searching for a late goal right up until the final whistle.
It never came.
''It was a game that just went to the extreme,'' Klinsmann said. ''We just needed a little bit more luck.''
Belgium had been criticized for its low scoring rate at the World Cup but it was not for want of trying on Tuesday. The team had 27 shots on Howard, compared to nine for the United States.
Amazingly, in the most lopsided knockout game so far, victory came preciously close for the Americans with seconds to go in regulation time when a goalmouth scramble brought the ball to Chris Wondolowski, who skied the ball over from the six-meter line.
It only served to set up a thrilling extra time.
''Now,'' Wilmots said, ''Belgium can celebrate.''
Belgium: Thibaut Courtois; Toby Alderweireld, Daniel Van Buyten, Vincent Kompany, Jan Vertonghen; Axel Witsel, Marouane Fellaini, Kevin De Bruyne, Dries Mertens (Kevin Mirallas, 60), Eden Hazard (Nacer Chadli, 111); Divock Origi (Romelu Lukaku, 91).
United States: Tim Howard; Fabian Johnson (DeAndre Yedlin, 32), Matt Besler, Omar Gonzalez, DaMarcus Beasley, Geoff Cameron; Michael Bradley, Jermaine Jones, Alejandro Bedoya (Julian Green, 105), Graham Zusi (Chris Wondolowski, 72); Clint Dempsey.
Follow Raf Casert on Twitter at http://www.twitter.com/rcasert