The nation that thrilled the world with the emerging power of African football by reaching the quarter-finals in the 1990 tournament have not been on such great form in recent years.
But spearheaded by striker Samuel Eto'o, they have rediscovered their roar under coach Paul Le Guen and will carry the hopes of many people not just in Cameroon but across the African continent as it hosts its first World Cup.
Japan are putting on a brave face but they have struggled to score goals and look destined to be the supporting cast in Group E, which also features Denmark and Netherlands.
Eto'o will need to put a spat with former Cameroon great Roger Milla behind him when he leads his team out at Bloemfontein's Free State Stadium.
Milla questioned the Inter Milan player's commitment to his country, prompting Eto'o to threaten to miss the tournament. But the three-times Africa Player of the Year had a thumbs-up and smile for the crowd when he arrived in Durban on Thursday.
Frenchman Le Guen, who has turned Cameroon around since his appointment in July last year, said the strong and experienced squad was in good fettle despite the Milla/Eto'o row and the failure to win any of their warm-up games.
"We had a good preparation and we are optimistic," he said. "We have pressure but it's not a surprise for me. It's normal. We have good players, we have a good team, I am hopeful."
The partnership of Jean Makoun and Alexandre Song in central midfield will also be crucial if Cameroon are to repeat former glories and dance once more around the corner flag, as Milla memorably did in 1990 after scoring.
The Lions were the first African side to reach the last eight and have the most appearances by any African nation.
JAPANESE FAILURE
Struggling Japan have failed to win a World Cup match on foreign soil and are desperate to find their scoring touch.
Fans of the Blue Samurai will place their hopes on attacking midfielder Keisuke Honda, who might even be used as a striker.
"I have practised this way of playing form time-to-time and I have been told there is possibility of having this role," the 23-year-old told reporters after Japan laboured to goalless draw against Zimbabwe in their last warm-up game on Thursday.
"It is the first time for me to take that role and I found it fairly comfortable. The playing time was short but I had a good number of chances. We didn't score but created some good attacking patterns," he said.
The Zimbabwe result followed four matches in which Japan managed just one goal, in a 2-1 defeat by England.
Midfielder Makoto Hasebe acknowledges the lack of firepower is a problem but still believes Japan have a fighting chance.
"Our problem in scoring goals is an issue that has needed addressing for quite some time and it is something we are acutely aware of," he said.
"I think we have a real chance of beating Cameroon as they are not at their best. It won't be easy, of course, but the main thing is that we are all in top c
