"We really like living in St. Petersburg, where the sun shines constantly and there is no night. These are the white nights. We need to curtain the windows to get enough sleep, but we like it here. Anyway, we'll have to leave soon," Ruiz told journalists.
"We respect Brazil, they are a good opponent. But anything can happen in football. We have prepared well mentally to succeed in the upcoming match," Ruiz added.
Ruiz also told journalists that he hoped his team can score and defeat Brazil.
"For us as a team, the game tomorrow is very important, it is very motivating to play against such a team as Brazil. Tomorrow it will be decided for both teams who have a chance of qualifying for the next stage. This will be a very intense match… and will try to score and win," Ruiz told journalists.
The 32-year-old forward added that the team will do "everything to score first in the match with Brazil" and will "play better tactically" than in their previous game.
The team also has to play against Switzerland during the group stage of the World Cup in Russia.
The 2018 FIFA World Cup kicked off on June 14 and will continue until July 15, with the matches set to be played in 11 cities across Russia.