The match in Johannesburg pits the FIFA World Cup's largest and smallest nations in terms of population and land area, and it is Slovenia, with about two million people, that can reach the last 16 by downing the USA, which has about 300 million people.
After a 1-1 opening draw with England on Saturday, the Americans find themselves needing a victory to overtake Slovenia, who were 1-0 winners over Algeria in the other Group C opener.
USA coach Bob Bradley believes the Slovenia game might be "more of a chess match" compared to the fast and physical pace of the match against England. "They are a hard-working team," said Bradley. "They are organized. They have an ability to sit back a little more and still get you on the counter."
"It's going to be very difficult as the tournament goes on and the results get more crucial," added USA defender Oguchi Onyewu.
Medically, there was good news for the Americans on Monday as goalkeeper Tim Howard was diagnosed with bruised ribs and although he was set to undergo further evaluation on Monday, Bradley expects him to be ready to face Slovenia.
Bradley was pleased at how the USA team, with seven players making their first FIFA World Cup appearance, held strong after falling behind 1-0 to England just four minutes in, something he credited to the character of his team. "The mentality of the group is strong," he said. "We have been hardened along the way and we believe that we can play against tough teams, top teams. We know the mentality of how 90 minutes works."
Meanwhile, USA defender Steve Cherundolo has received numerous well-wishing e-mails from pleased US supporters back home. "The general public is proud of our performance and that's something this team can be proud about and build on," he said. "At the end of the day, results matter more than anything. No matter how you play, nobody wants a loser."