Uruguay and Barcelona striker Luis Suarez said his rivalry with Portugal and Real Madrid forward Cristiano Ronaldo was different when they are playing for their respective countries in comparison to when they play for their clubs.
The quarter-final match between Uruguay and Portugal will take place in Sochi on Sunday (4am AEST).
"A match-up between Spanish sides Barcelona and Real Madrid, also known El Clasico, is one of the biggest rivalries in sport," Suarez said.
"A rivalry with Ronaldo here (at the World Cup) and at a club level are two different things. This is the World Cup and we are playing for our national teams."
The 2018 FIFA World Cup kicked off on June 14 and will continue until July 15, with the matches being played in 11 cities across Russia.