Austria beat the United States in extra time on Saturday to go into the semi-finals of the Under-20 World Cup where they will meet the Czech Republic, who beat Spain on penalties.

Austria came from behind for a surprise victory after the U.S took the lead in the 15th minute when striker Josmer Altidore headed home Freddy Adu's cross.

Two minutes before the break Austria drew level when U.S keeper Chris Seitz failed to hold on to a long-range shot and Rubin Okotie slotted home the loose ball.

The game turned Austria's way though two minutes before the end of the first period of extra-time when American defender Anthony Wallace was dismissed with a second yellow card and from the free-kick he had given away substitute Erwin Hoffer knocked in the winner.

After a goalless 90 minutes in Edmonton, the Czech Republic went ahead through a powerful Lubos Kalouda drive late in the first period of extra-time.

Juan Manuel Mata equalised for Spain with five minutes remaining, tapping in after Alberto Bueno's shot came out off the post.

Bueno then missed a great chance to win the game for Spain with almost the last kick of the match but screwed wide and the match went to penalties.

The Czechs won 4-3 in the shoot-out, Marc Valiente and Gerard Pique failing to score their penalties for Spain.

Chile face Nigeria, and Argentina meet Mexico in Sunday's quarter-finals.

• Complete football coverage