A second half strike from Thomas Muller gave Germany a 1-0 victory over the United States on Thursday, a result that saw both teams through to the World Cup knockout phase.

Muller assured his team top spot in Group G when he fired in a long-range effort in the 55th minute at the rain-logged Arena Pernambuco.

The result left the US second in their group, ahead of Portugal on goal difference after the latter's 2-1 victory over Ghana in Brasilia.

Germany face the runners up of Group H in Porto Alegre on June 30 while the US will meet the Group H winners in Salvador a day later.

Both teams entered Thursday's match needing only a draw to progress to the round of 16.

As expected, Germany controlled possession and looked more threatening in attack on the slippery pitch.

Muller was denied twice in as many minutes by stubborn defending from Omar Gonzalez.

But the USA also had their share of chances and were unlucky not to go ahead when Graham Zusi's shot when inches over the bar.

Shortly after, Jermaine Jones ran onto a long ball but failed to control the skidding bounce when he only had goalkeeper Manuel Neuer to beat.

Mesut Osil then drew a fine save from Tim Howard after the Arsenal midfielder's jinking run from the left flank.

Germany coach Joachim Loew introduced striker Miroslav Klose at halftime and the move almost paid off immediately.

Philipp Lahm found Klose with a precise cross but the Lazio forward's header missed the target.

Germany finally broke the deadlock just before the hour.

Per Mertesacker's header was parried away by Howard but Muller fired the rebound into the bottom corner from outside the area.

The US refused to surrender and had several chances to equalize in the final minutes.

Captain Clint Dempsey headed over and then Alejandro Bedoya saw his effort cleared by a lunging Lahm.