(Reuters) - Greece wasted a golden opportunity to beat 10-man Costa Rica in extra time before exiting the World Cup on penalties, coach Fernando Santos said on Sunday.

Leading 1-0, the Costa Ricans struggled to hold on following the dismissal of defender Oscar Duarte after 66 minutes of the last 16 clash.

Greece hauled themselves back into the game to level in stoppage time, but failed to make their numerical advantage count in extra time, eventually losing 5-3 on penalties.

"I don't think we used the 30 minutes (of extra time) as well as we should. We started it as if it was the last minute of the game, but there was still 30 left," the Portuguese-born Santos told a news conference.

"We just needed to pass it around well and go into their half of the field and do things well. We were controlling the game, but then we wanted to try to finalize things individually," said Santos, who was sent to the stands for arguing with the referee before the penalty shootout.

He praised Costa Rican goalkeeper Keylor Navas, whose superb acrobatic save from Theofanis Gekas's fourth spot-kick proved to be the difference between the two sides.

"Navas, he was the real protagonist today, he saved three or four goals, two in particular were very good moments for him," said the 59-year-old, whose contract as Greece coach runs out on June 30.

"Obviously he has to be congratulated, I think if it wasn't for him the result would have been different."

Santos was circumspect about the result that brings the curtain down on his four-year spell in charge of Greece.

"I don't really like talking about luck or lack of luck, Costa Rica won, obviously they were better in what was expected," he said.

"It can go either way, and it went to Costa Rica, they won and they go on. For that they have to be congratulated."