The United States' dream of an unprecedented last four place at the World Cup remains on track, but after a scrappy 1-0 defeat to Germany the Americans admit they must do far better if they are to get past Belgium.

Germany dominated proceedings at a washed-out Arena Pernambuco where the US were restricted to only two chances in a startlingly one-sided game settled by Thomas Mueller's second-half strike.

Mueller's 55th minute goal, his fourth of the tournament, kept the Germans undefeated and top of Group G to set up a last 16 clash against Algeria, who got the point they needed with a 1-1 draw with Russia, while the US, who finished second ahead of Portugal and Ghana, will now meet Group H winners Belgium.

Belgium rounded off their group campaign with a 1-0 win over South Korea to end with a perfect nine points from three games.

The gulf in class between Germany and the US means the latter could struggle if they are to go one step further than their quarter-final appearance in 2002.

Germany's short, slick passes, interchanging of positions and movement off the ball had the Americans in trouble from the outset and was a stark contrast to a performance defender Matt Besler described as a "grind".

"We all understand that we're going to have to play better. This is the round of 16 for a reason... we're going to have to keep the ball better," said Besler, who was kept especially busy during the first-half as Germany launched wave after wave of attack.

"Germany is a very difficult test. The way they play, the way they keep the ball. It's never just one guy you have to look out for, it's (Mesut) Ozil, it's (Thomas) Mueller, even (Philipp) Lahm was making runs in behind," he added.

"They did a great job, interchanging positions, moving off the ball, playing simple. I would say that's the one thing we're maybe disappointed in, how we didn't keep the ball."

"Ok today wasn't the best day, but it was Germany," admitted US midfielder Jermaine Jones, who is sporting a suspected broken nose having first run blindly into match referee Ravshan Irmatov before clashing with teammate Alejandro Bedoya.

"Of course we have to control the game a little bit better."

US coach Jurgen Klinsmann, who won the World Cup with Germany as a player before leading the Mannschaft to third place as coach in 2006, admitted: "Obviously we would have liked to create more chances and find more ways to take it to Germany.

"Germany are among the four or five favourites for the title. We're still growing, we're learning."

The US now have five days to prepare for Belgium, who won three games and drew the other to top Group H.

"They're a top side, with a lot of quality players," said US captain Clint Dempsey, who had got on the scoresheet in their previous two games.

"You have to make sure you stay compact defensively, but at the same time we have to be more on the front foot, play our game, play more the way that we did against Portugal than we did today."

Meanwhile, in rainy Recife, where thousands of US fans struggled to get to the game in time amid torrential rain that halted traffic throughout the city, US shortcomings were being put to one side.

"We have a very, very strong team and the players are so hungry to do well," added Klinsmann.

Besler added: "It was a grind, for sure. All three games were tough, physically. There were a lot of ups and downs emotionally. But that's what it's about.

"The great thing is, now we're through. We can find that extra level now we're through to the next round."

Asked to express his feelings at the final whistle, Besler added: "Joy, relief, proud of the effort we put through.

"Anything can happen in this tournament. It's one game, if you play well enough to win you go through. We're going to give evrything we have and see what we can do."