Costa Rica and the United States met behind closed doors on Thursday - but the details of the match were kept from reporters waiting outside.
Ticos coach Alexandre Guimaraes did confess that his players were feeling the strain afterwards.
He added that they might need to play more conseravtively in their opening game against China on 4 June as a result.
"They are tired after long club seasons," the coach said. "We will have to adapt our tactics.
"We are usually very attacking, but I think we must concentrate on holding the ball up in midfield."
Despite the lack of information about the match, it was revealed that Mancester City striker Paulo Cesar Wanchope had taken part.
Guimaraes apparently used 22 of his 23-man squad in a match that was more of a tactical exercise than a proper game of football.
The result was kept secret, apparently, at the request of the US squad.
However Costa Rica and the United States are well acquainted with each other having met twice during World Cup qualifying.
Costa Rica won 2-1 at home, while the teams played out a goalless draw in the States last October.