Costa Rica coach Oscar Ramirez has warned critics that he has "a tiger inside" and is not prepared to accept some of the personal comments aimed his way in recent days.

The 2-0 defeat to Brazil last Friday, in which Philippe Coutinho and Neymar scored in second-half injury time, ensured Costa Rica head into their final Group E game against Switzerland in Nizhny Novgorod knowing they cannot progress to the last 16.

Expectations were high back at home following the run to the quarter-finals in Brazil four years ago, and there has been significant criticism of both the team and Ramirez himself, some of it deeply unsavoury.

And the 53-year-old says he will not tolerate those who accuse him of being "a coward" and is adamant he will not be forced to walk away from the job.

Asked how he felt about the critics, he told a news conference: "I'm hurt and disappointed.

"Of course, I wanted to make our country happy. I really didn't want to go through what we have gone through. We had a very tough group and personally some people were saying tough things.

"People who know me know I'm not going to give up. Some people have hinted at that but I'm not going to go away. It's true the things being said are quite hurtful, they've talked about things that aren't relevant, like weight problems, languages and now they talk about things like my own dignity.

"I can sleep well because we've done our best, but saying I'm not brave enough or a coward, I'm not going to tolerate it. If they attack me or my family, I'll show them there is a tiger inside me."

Panama boss Hernan Dario Gomez claimed teams from the Americas are finding it tough to perform to their best in Russia, with his side having been dispatched 6-1 by England at Nizhny Novgorod Stadium only two days ago.

However, Ramirez believes Brazil, Uruguay and Mexico in particular have shown themselves to be potential challengers for the trophy.

"We've played many matches over the last two years and maybe games are different in CONCACAF and we don't have the same level that other teams here have, so maybe that's one of the reasons the Panama coach said that," Ramirez said. 

"We've had some problems in Europe in World Cups and I'd say Brazil are good candidates for winning, Mexico as well. They might be the surprise of this tournament. Uruguay are also there, they won three matches, and we'll see what happens with Argentina."