For the United States, it’s time to put up or shut up.

On Sunday we find out if the stepchild of American sports is ready to become a full-fledged adult, or whether it’s destined to be a temperamental teenager for another four years.

If the Americans are intent on becoming a global force, if they want to be meaningful players on soccer’s greatest soccer stage of them all, then they need to avoid defeat against Portugal.

The USA is rated 13th in the FIFA world rankings (above the Netherlands and France), but in the soccer hot spots of Europe and South America, they are still not taken seriously. Through no fault of their own, the rankings are weighted in their favor; there is a built-in bias toward the Americans.

Teams receive the most points for competitive games, and for obvious geographic reasons, the majority of those matches are against their fellow CONCACAF members in North and Central America. There is a saying in soccer that you can only beat what is in front of you. But it’s not being disrespectful or insulting — just realistic — to write that a country with 300 million people should regularly hammer nations like El Salvador and Panama.

In contrast to the States, who regularly pick up points in victories against lower-ranked nations, it’s much harder for European teams. Countries like the Czech Republic, Denmark and Sweden, none of whom qualified for the World Cup, contain talented players from the elite soccer leagues. But they get drawn in qualifying groups with nations like Germany, Italy and Spain, and it is much harder for them to rise in the rankings.

The USA has turned in some great displays in friendlies against European powerhouses recently, but they are exactly that — friendlies. And it’s only once every four years they get to test themselves against true world superpowers. The Americans may never have a better chance than they have this weekend to prove that they deserve their lofty position on the edge of the top 10.

I wrote it last week, and I repeat it today: The Americans should not fear Portugal. I watched them in qualifying, and they failed to beat Northern Ireland and Israel at home. It took a fantastic individual performance from world player of the year Cristiano Ronaldo to get them to the finals, as he scored a hat trick in the second leg of the playoff against Sweden. Stop Ronaldo, and you stop Portugal. With a bit of luck, they may not even have to stop him, as there were questions over his fitness coming into the tournament, and he limped out of training earlier this week.

Through injury and suspension, the Portugese are missing three of their first-choice back four. They were swatted almost contemptuously aside by the Germans in their first game. They looked like an unhappy, disjointed team in disarray. Furthermore, the heavy 4-0 defeat in their opener means they have to win their second match.

Their success has been built around the devastating speed of Ronaldo on quick, decisive counter-attacking soccer — and instead, in Sunday’s contest, they will have to be on the front foot from the kickoff. All the USA needs to do is tie, and it will probably be safely through to the next round.

Can the Americans handle the pressure? Can the relatively inexperienced squad, with many players more used to playing in front of 15,000 fans in Kansas City than before a global audience, cope with the stakes of a make-or-break World Cup contest? Can they soak up wave after wave of attacks, slow the game down, defend for 90 minutes, waste time and frustrate and needle the Portuguese?

Teams talk about winning ugly, but can they tie ugly? Can they sit back with 10 players behind the ball and say to their opponents, “C’mon then, are you good enough to break us down”?

The Americans deserved the win against Ghana, but without the right result Sunday, it will count for nothing. If they can secure a draw on Sunday, it means that they could probably lose to Germany in the next game and still make the knockout stage. However, if Portugal wins, the Americans could beat the Germans and be on their way home regardless.

So, USA, put your money where your mouth is. Show the world you are ready to grow up and become a soccer adult. And prove to the world that you deserve your place at the big boys’ table.