Brazil captain Thiago Silva has warned his colleagues to be concerned by the threat posed by Cameroon's Samuel Eto'o.
The Selecao open the World Cup against Croatia on Thursday before facing Mexico in Fortaleza next week.
The hosts will meet Cameroon on the final Group A matchday on June 23 and the Paris Saint-Germain skipper knows four-time African Player of the Year remains a tough opponent, despite the player having clashed with Chelsea boss Jose Mourinho over comments concerning his age this season.
"He is the striker who most worries me," said Silva, who faced the 33-year-old in the quarter-finals of the Uefa Champions League with Chelsea last season.
"He is an experienced player and a handful to deal with. In the Champions League he wasn't 100 per cent but he made his presence felt.
"He has impressive technical abilities and is lethal in the box."
Eto'o's countryman Stephane Mbia, meanwhile, hopes this year's finals can help to banish the memories of the tournament in South Africa in 2010, when Cameroon lost every game and crashed out at the group stage.
"Four years ago we were catastrophic," he said. "The mood in the camp wasn't good, there were a lot of problems.
"But this time that's not the case. We'll be making our mark on this tournament."