Alexis Sanchez and the pace of Chile's forwards pose the major threat to Brazil's World Cup chances ahead of Saturday's last 16 meeting between the South American rivals, according to Brazil defender David Luiz.

"I wanted us to get through and now I am happy," said the 27-year-old after the Selecao beat Cameroon 4-1 in Brasilia on Monday to seal their place in the first knockout round.

Of Saturday's impending clash with Jorge Sampaoli's impressive side in Belo Horizonte, he added: "Chile are a team who deserve to be there. They have a philosophy of playing good football. They have lots of pace and excellent players."

Chile impressed in beating Australia and then eliminating holders Spain in their first two World Cup matches before a 2-0 defeat to the Netherlands in Sao Paulo on Monday ensured left them second in Group B.

As a result, they are set for a third meeting with Brazil in little over a year -- the sides drew 2-2 in Belo Horizonte in a friendly in April last year before a 2-1 Brazil victory in Canada last November.

However, Luiz added: "History counts for nothing. We want to win. What is the biggest threat that they pose? The whole team."

The performances of Chile's unsung heroes such as midfielders Marcelo Diaz and Charles Aranguiz have caught the eye at this World Cup, but Arturo Vidal and Alexis Sanchez are sure to have key roles to play if Chile are to get the better of the hosts.

"I always speak to Alexis on the phone. Now we are going to come up against each other," said Neymar, a club colleague of Sanchez at Barcelona, after scoring twice in the victory against Cameroon.

"Alexis is a star. I admire him a lot. He is a great player and we will need to be careful with him. We can't leave him any space."

Along with the craft of Neymar, Brazil's central defensive pairing of captain Thiago Silva and David Luiz is their biggest asset in many people's minds.

However, they have at times been exposed in the full-back positions at this World Cup, with both Dani Alves and Marcelo guilty of pushing forward and leaving space in behind.

Against the constant movement of Chile's attack, Alves, another colleague of Sanchez at Barcelona, knows that he will need to be wary.

"Alexis Sanchez is one of their most dangerous players. Of course Chile have others but Alexis makes the difference," said Alves, before insisting that Brazil are slowly emerging as genuine contenders to win the tournament.

"We have been making strides ever since the first game. Now we have made it to the last 16 with confidence and that boosts our chances.

"Since the first game we have improved as we hoped to do."