A 21st minute goal from Diego Lugano gave the Charruas the upper-hand going into the second leg on Wednesday in Montevideo.

Costa Rica played the last 38 minutes with 10 men after the dismissal of Randall Azofeifa, and Tabarez expected his team to take advantage.

"This result is very important," he said. "Winning away is not easy. We have passed a very difficult test in a very even game.

"The 1-0 score is excellent, but we are unhappy with our form. Sometimes, we controlled the game and Costa Rica's most skilful players.

"But Costa Rica's most dangerous spell was when they were playing with ten men and we made a mistake by playing too defensively in the second half.

"Costa Rica showed calmness even with ten men. This match is now in the past. We are focused on Wednesday. We have had a dream for three years and a half and we have the chance to make it come true."

Tabarez was also unhappy with the surface at the Estadio Ricardo Saprissa, which has artificial turf.

"It was terrible," he said. "We weren't used to it.

"It was a strange field for us. On Wednesday, we must improve and I expect a different match."

Costa Rica boss Rene Simoes, meanwhile, focused on his team's improvement in the second half.

He said: "The first half was decisive. Our form was too poor. In the second half, we started playing, even with ten men. We played head to head.

"If we had played the first half the same way we played after the break, we would have seen another result."

But the Brazilian-born Simoes, who coached Jamaica in the 1998 World Cup Finals, encouraged Costa Ricans to keep supporting the team.

"We must believe we can qualify," he said. "This is not over.

"There are 180 minutes. We are 1-0 down in the first half. It is not over at all. In 1950, Uruguay won the World Cup at the Maracana. Why can't we win at the Centenario?"