Problems mounting for underdogs Honduras
"He is depressed and a bit irritated because of this situation just a few hours from the start of the first game," Rueda, who is banned from the dugout and will watch from the stands, said of De Leon's injury suffered on Monday.
A Honduran spokesman was not able to give details of the injury other than to say it was a "muscle strain."
Forward David Suazo is also struggling after picking up an injury in his right leg during a friendly with Romania earlier this month.
Doctors will evaluate both players but should they miss the game De Leon, nicknamed "Rambo" after Sylvester Stallone's tough-as-nails movie character, plus Suazo will be a big loss for Rueda.
Honduras, rocked in June 2009 by a military coup, are appearing in only their second World Cup after their debut in 1982 and will have to face Chile without Rueda in the dugout after he was sent off during the tiny Central American country's qualifier against El Salvador last October.
Captain Amado Guevara said Colombian Rueda, who was granted Honduran citizenship in April for guiding the country to the finals, would be missed but would be on the phone with the rest of the technical team during play.
"We all know that he's our teacher and we will feel his absence tomorrow," he said, adding his team have no issue with the on-trial synthetic and grass pitch.
"It is nothing new for me because I've played a number of years in the United States - I don't think this can serve as an excuse not to play well tomorrow against Chile."