Fernando Santos admits it would be foolish for his Greece team to under-estimate giant-killers Costa Rica, who will look to make history in Recife on Sunday.

When Costa Rica were placed in Group D at the World Cup draw in the opulent holiday resort of Costa do Sauipe last December, there seemed little hope of the Central American nation making it through to the second round.

But six months later, Costa Rica took everyone by surprise, out-smarting three former world champions to progress to the last 16.

Jorge Luis Pinto's men stunned Uruguay 3-1 and then beat Italy 1-0 to send England out of the tournament with one match to spare.

Their progression to the last 16 has been one of the good news stories of the tournament so far and it has also made Greece wary of what awaits them in the Arena Pernambuco on Sunday night.

"We have to pay a lot of attention in this game, they came out top in the 'Group of Death'," Greece coach Santos told a press conference.

"As a result we cannot allow ourselves to underestimate them."

Costa Rica's squad contains players from unheralded teams like Kuban Krasnodar, Alajuelense and Columbus Crew, but they have won many admirers for their flamboyant attacking football.

Off the pitch, the players are not so flamboyant. They are understated and calm about the prospect of making it through to the quarter-finals for the first time.

"To have qualified top of the group makes us proud," defender Michael Umana said.

"It gives us great satisfaction as a group. We have grown as a team although we have always been characterised by strong and silent work."

With so much riding on the match, Costa Rica would be forgiven for adopting a more cautious approach in Recife, where thunderstorms are expected on Sunday night.

And if there is no winner after 120 minutes, Costa Rica will be prepared for what comes next.

"Penalties could play a crucial role at any moment," Costa Rica assistant manager Luis Marin said.

"So we have been practising them for the last few days and we know who will take them."

Costa Rica are expected to name the same XI that beat Italy in their penultimate qualifier.

Greece, who qualified thanks to a controversial last-minute penalty against Ivory Coast, will be without midfielder Panagiotis Kone through injury.

Goalkeeper Orestis Karnezis should be fit despite suffering a knock against the Africans.

Santos must decide whether to recall captain Kostas Katsouranis, who was suspended for the Ivory Coast match.

The winner of Sunday evening's match will take on either Mexico or Holland, who play earlier in the day, in the quarter-finals.