Costa Rica coach Jorge Luis Pinto Friday said the referee should consider sending off the Netherlands' self-confessed diver Arjen Robben if he catches him cheating in their World Cup quarter-final.

Pinto said he was "really worried about Robben diving" and he urged Uzbek official Ravshan Irmatov not to be afraid to give him two yellow cards for simulation if necessary.

His comments come after Robben won a match-deciding penalty in the Netherlands' 2-1 last-16 win over Mexico and then admitted diving earlier in the game.

"This is one of the most important questions I have been asked. In this World Cup diving is something that has us worried," Pinto told journalists in Salvador.

"We're really worried about it. I would like to ask FIFA and the referees to watch Robben closely.

"I think Robben is one of the three or four best players in the world. I have a website, jorgeluispinto.com where I analyse him as a player. He's amazing, he's a great player.

"But on the other hand there have been refereeing mistakes and the referees need to watch out."

Robben, 30, went unpunished by FIFA but his comments prompted much condemnation and debate. He has scored three goals in the World Cup and will lead the attack on Saturday.

"We're really worried about Robben's diving. He admitted that he dived so I hope the next referee and assistant referees are very careful tomorrow," Pinto said.

"I respect them a lot but I tell them: watch out. I hope there are no mistakes... so I would like to ask FIFA and the referees to watch out because this is very, very important and it could have an impact on the result."

Asked whether Irmatov, 36, should book Robben early if he suspects him of diving, Pinto said: "Well that might be the most logical solution.

"Maybe he would have to leave the field because he gets two yellow cards for diving. That could happen. But I want to trust the referees -- let's see what they do tomorrow."

Wins against Uruguay and Italy helped Costa Rica top a tough Group D and they then beat Euro 2004 winners Greece on penalties despite playing for an hour with 10 men.

However 'Los Ticos' remain firm underdogs against a Dutch team which has won four in a row, hitting five past reigning champions Spain at Salvador's Fonte Nova Arena.

Pinto said he had been taking advice from Fulham forward Bryan Ruiz, who has played for FC Twente and PSV Eindhoven in the Dutch championship.

And despite the pedigree of the Netherlands, who were runners-up to Spain four years ago, defender Johnny Acosta said Costa Rica would not be overawed.

"We're not scared at all. In Costa Rica we always say that worse things happen at sea," Acosta said.

"We're very motivated," he added. "We're very happy to be here and we want to keep writing history for our country."