Belgium coach Marc Wilmots said he wants to "surprise teams" and praised his side's depth as they eased to the top of Group H with a 1-0 win over South Korea on Thursday.
Wilmots' men advance to play the United States, the runners-up from Group G, in the round of 16 on Tuesday.
Belgium easily handled the U.S. 4-2 in a friendly in May 2013, but Wilmots said their next game will have a different atmosphere.
"This match won't be as friendly," he said. "It is a new competition and [the U.S.] have a talented group. Even if we are supposed to be the favourite team, we are used to that. We've made history and I would like to congratulate both the staff and the team.
"I use the qualities of my core players, but I want to surprise my opponent. Today they were surprised. Everyone is important. The team spirit is important and it makes me happy to see that. This is something we've been working on for the past two and a half years.
Wilmots' men rallied for victory against South Korea despite losing Steven Defour to a red card just before halftime, and the manager said he was pleased with how his players adjusted to a new strategy after going down to 10 men.
"I couldn't really see it, but it's a pity for Steven," Wilmots said. "We were playing with a new formation. We were doing well and all of a sudden we were faced with a red card.
"Two minutes later we went to the dressing rooms and we wanted to play with two lines of four and close the inside of the midfield and leave the flanks open. It's also a matter of patience and not rushing forward too quickly. I knew the Koreans needed to win and wanted more space."
Belgium were already through the the knockout stage before the game and made several changes to their lineup, with four players getting their first taste of the World Cup.
Injured captain Vincent Kompany and Thomas Vermaelen sat out, as did yellow-carded Toby Alderweireld and Axel Witsel to make sure they are not suspended for the second round. Playmaker Eden Hazard was also benched.
"I'm here to set up a group. Everybody except one or two players has played," Wilmots said. "We want to reach the knockout stage. Either you go back home or you continue. I wanted everybody to be fresh. I spared those who I thought I could spare.
"Everybody is at the same level with the same experience. We are well equipped to go to the next stage and the objective is to win all our matches."
Belgium triumphed in one of the easier groups at the World Cup, but Wilmots did not back down from the challenge that awaits in the knockout stage.
"Whatever the style of play, we are here with the best teams on Earth," he said. "We're here to win and we've showed that we don't have 11 players. We have 20 or even 23 good players and we can surprise teams. We've fulfilled our mission and we are ready to reach the quarterfinals."