Germany defeated the USA, 1-0, in a World Cup quarterfinal clash on Friday in Ulsan, South Korea. Michael Ballack scored the gameÆs only goal in the 39th minute. He outjumped U.S. defender Tony Sanneh at the edge of the goal area to reach a Christian Ziege free kick and head low under Brad FriedelÆs arm. Oliver Kahn twice denied Landon Donovan with excellent saves. After Germany took the lead, Miroslav Klose headed against the post for its best chance before halftime. The United States enjoyed some periods of extended possession in the second half and came closest with two Sanneh headers that flew wide of the German goal. A Gregg Berhalter volley — from inside the goal area off a Claudio Reyna corner kick — in the 50th minute came teasingly close to crossing the goal line before Kahn got a handle on it after it hit Torsten Frings' arm. Referee Hugh Dallas did not call a penalty kick. He either didn't see it or decided that Frings' handling was unintentional. ''The Americans were top fit and kept trying for 90 minutes, putting us under a lot of pressure,'' said Ballack. ''They proved their presence in the quarterfinals was no accident. They deserved to be at that stage. ''We knew that at set pieces were one of our strengths. I'm happy that it works out well but it was a lot of hard work and we also had a bit of luck.'' In its semifinal on Tuesday, June 25, Germany meets the winner of South Korea-Spain.