Updated JUN 27, 2014 2:33a ET  Getting through the group stage at the World Cup deserves a more substantial reward than the fleeting satisfaction of a job well done. It is hard to negotiate three games against difficult opponents and secure enough points to advance. It is even more difficult to climb out of a four-team pool better known as the Group of Death and find a way past two of Germany, Ghana and Portugal in order to survive.  Instead of an extended lap of honor and a week or two to rest those weary legs after finishing second in Group G, the United States men's national team must immediately shift its focus to a more daunting challenge. It must start its path through the knockout stage -- a perilous journey even thornier than the thicket just conquered -- with a date against Belgium in Salvador on Tuesday.  Forget about the modest safety net of the three games in round-robin group play. It is gone. Ignore the possibility of losing, too. The World Cup isn't like the NBA or the NHL playoffs where the adversaries play a seven-game series to determine which team advances to the next round. It isn't even the UEFA Champions League where the combatants play two matches to determine the winner in the Round of 16, the quarterfinals and the semifinals before a one-off final.  This is a knock-down, drag-out single elimination tournament from this point forward. Sixteen teams will start along the road to lifting the trophy when the Round of 16 kicks off on Saturday. Only one of them can emerge victorious at the end of the road in Rio de Janeiro on July 13.  Every match must have a winner. If the game is tied at the end of 90 minutes, then the two teams play 30 full minutes of overtime to break the deadlock. If the score is still tied at that point, then the sides take penalty kicks -- five at the start, more if needed to snap any remaining ties -- until one country prevails.  Advancing through this gauntlet is even harder than it sounds. There is a reason why only eight countries have ever won the World Cup. It is because there is no room to hide after group play ends, no way to sneak through without the conviction, the guile and the talent to win four consecutive matches in a short space of time.  Take, for instance, the potential road ahead of Team USA over the next few weeks. In order to lift the title, this group would need to beat four teams in four different cities within a 12-day period. It almost makes the 9,000-mile-or-so journey to play three group stage matches look like a relative cakewalk.  Belgium is only the first step. If the Americans defeat the Belgians, then they'd likely play Argentina in Brasilia four days later. And then they could face the Netherlands (or Mexico or Costa Rica, but probably not Greece) four days after that game in Sao Paulo. And then Brazil, Colombia, France or Germany in the final at the Maracana Stadium four days after that.  There is no margin for error on that perilous march. Every match is decisive: Win and stay for another game, lose and go home. It creates drama and tension along the way. The format levels the playing field between good teams and bad because it requires every team to perform well on the day in order to progress. There is no tomorrow without delivering today.  It is a problem the United States knows only too well: This team -- despite the usual snide remarks from distant quarters -- have reached the knockout stage three times since starting its run of seven consecutive appearances back in 1990. The Americans fell at the first hurdle in 1994 and 2010 and reached the quarterfinals once with a famous dos-a-cero over Mexico in 2002. And the United States record is much, much better than a lot of countries incapable of reaching the Round of 16 or advancing past it every so often.  Those stark facts underscore why the United States should revel in its achievements to date without glancing away from the task at hand. The job isn't done yet. There is more still to do with a confident squad filled with belief and conviction after its group stage success. The only problem: It can all disappear in an instant now. It is both the beauty and the danger of the challenge looming when the knockout stage starts for the Americans on Tuesday.
The U.S. national team clinched a berth in the knockout stage on Thursday. What comes next for the Americans? And what is the knockout stage, anyways?