Diogo Costa
This guy is Portugal's last line of defense and he's got ice in his veins—at just 23 years old, he's already one of Europe's most impressive shot-stoppers with lightning-fast reflexes. He matters at this World Cup because Portugal's aging star Cristiano Ronaldo needs a rockstar defense in front of him to make a deep run, and Costa has the skills to keep them in games they might otherwise lose. If you're watching Portugal play, keep your eye on how calmly he handles pressure situations—he rarely looks rattled, which is basically the goalkeeper superpower. Think of him as the young, cool-headed guardian who could be the difference between Portugal going home early or making a surprising run toward the trophy.