Germany defender Mats Hummels said United States' performances at this summer's World Cup have exceeded his expectations.

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Germany face the U.S. in Recife on Thursday with both sides well placed to qualify from Group G, which had been billed a group of death when the draw for the tournament was made.

After the U.S. saw off Ghana 2-1 and then drew 2-2 with Portugal, they know any kind of positive result will see them into the round of 16, with Germany almost certain to join them.

"USA have surprised me," Dortmund centre-back Hummels said. "They have good players, but have also translated that into performances on the pitch. Beforehand, I did not expect it to be like this, but that's certainly down to my own ignorance.

"They are powerful opponents, and it won't be easy beating them. We've already seen that when losing 4-3 [in a Washington friendly] last year."

While both teams know a draw would see them into the next round, Hummels dismissed any suggestion that the teams could ease off and settle for a point apiece.

"It would be highly unsportsmanlike to even think about something like that and, also, it's not our style to play for a draw. Of course, if it's 1-1 in the 91st minute, I won't try and dribble past four opponents in our defence," he said, before joking: "... maybe two."

Germany had begun their campaign in Brazil in highly impressive fashion with a 4-0 demolition of Portugal before struggling to a 2-2 draw with Ghana on Saturday.

After that performance, Hummels had been critical of his teammates and complained that they had ceded possession too easily prior to the Ghana goals, albeit without singling anyone out.

Earlier on Monday, German public radio ran a feature about a possible rift in the national team over Philipp Lahm's role in holding midfield. The captain had given the ball away before the second goal, and Shkodran Mustafi, who had replaced Jerome Boateng at right-back, was also culpable.

On Monday morning, the tabloid Bild and other papers also called for Lahm to return to the right-back position, but Germany assistant coach Hansi Flick insisted the captain would continue in midfield.

"Philipp Lahm is doing a really good job," he told the media. "We are satisfied, even if he played one or two bad passes on Saturday. These things happen. We see Philipp Lahm in midfield -- he gives our game structure."