The Qantas Young Socceroos have been beaten 3-2 by Costa Rica in their second group match of the 2011 U20 World Cup in Colombia.
Arsenal target Joel Campbell fired his side into the lead in the 22nd minute before Australia's Tommy Oar got his second goal of the tournament four minutes later.
Campbell added a second in the 27th minute but the Socceroos were able to level at 2-2 when Francisco Calvo scored an own goal just after the hour-mark.
But with just under 20 minutes remaining, John Ruiz headed home a Campbell corner to give Costa Rica a 3-2 victory, disappointing Australia coach Jan Versleijen.
"This is a very disappointing loss, though we played a very good game," said Versleijen.
"We were naive in certain parts of the game. If you make those kind of mistakes at this level, you will be penalised for that and that is what we faced today.
"We created some good chances, we scored good goals, but if you give away the goals, like we did today, at this level, you can never win the game.
Australia now has to beat Spain in their final group match to be any chance of progressing to the knockout phase.
"You must have hope. You have three games in the pool and from three games, you must have four points to qualify. We know now what our target is and that is to win against Spain," Versleijen added.
"So we have no other choice than find a game plan where we will be able to get a good result against Spain."
