The South American rivals meet in Belo Horizonte tonight for a place in the quarter-finals of the tournament.
"The next game is about who has more endurance and who has the mentality to go a long way," Sanchez is quoted as saying by Sky Sports News.
"We may not all be friends but on the pitch everybody runs for the other and this team is like a pitbull dog.
"On Saturday we're going to try to win the match and to keep accomplishing the dream that we all want, which is to win the World Cup."
Chile have been knocked out of three World Cup by Brazil, including in the last 16 of the 2010 tournament.