Cameroon lost 1-0 to Japan and Denmark were beaten 2-0 by the Netherlands in their opening games on Monday and both sides desperately need a win at Pretoria's Loftus Versfeld stadium to have a realistic hope of making the second round.
Cameroon's players are especially unhappy because Frenchman Le Guen omitted seasoned campaigners like defender Rigobert Song and Geremi and midfielder Alexandre Song from the Japan game.
"What we have seen in recent games, which we think is unfortunate, is that many young fresh players have been introduced into the team at the expense of experienced ones," midfielder Achille Emana told reporters on Thursday.
Cameroon, one of six African teams in the tournament, were expected to do well, but their chances now hang by a thread.
Emana said the young players had been asked to do too much.
"They cannot withstand the sort of pressure that comes with playing in big tournaments such as the World Cup," he noted. "That is why we are appealing to the coach to review the lineup for Saturday's game against Denmark."
Le Guen has not spoken to the media since Monday's loss and was conspicuous by his absence at Thursday's news conference.
Emana, usually an attacking midfielder, came on as a second half substitute against Japan but was also unhappy about the role he is expected to perform for his country.
"More often than not I am not fielded in my right position. I'm made to chase the ball all over the field. And, in that case, how do you expect me to be effective?" he said.
WINLESS STREAK
Including Monday's defeat, Cameroon have gone eight matches without a win and key striker Samuel Eto'o told reporters on Monday they needed to keep the faith.
"We played a good match from the beginning to the end. The Japanese had only one chance and they scored. We can't make any more errors and now we have to win against Denmark."
Despite losing their opener to the Netherlands, Denmark are ready to capitalise on Cameroon's woes.
Although naturally down after losing, goalkeeper Thomas Sorensen said the mood in their camp had remained upbeat.
"I think that is one of the good things about our team," he told Reuters. "We have a great team spirit - that's what has carried us through. One defeat is not going to bring us down."
Denmark have never lost to an African side at the World Cup, with a win and two draws in previous meetings, but they are struggling with injuries and strikers Jon Dahl Tomasson (thigh) and Mikkel Beckmann (toe) have had to train alone.
The Danes have not scored in their last three matches and coach Morten Olsen will be hoping striker Nicklas Bendtner, who played for just over an hour against the Dutch despite a groin problem, will be fit.
Young defender Simon Kjaer (knee) and midfielder Daniel Jensen (Achilles) have trained with the team but they are also suffering with nagging injuries.
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