Rio De Janeiro:The United States takes on Belgium for a place in the World Cup quarterfinals on Tuesday, a few hours after the day's action gets underway with Lionel Messi's Argentina playing Switzerland.
Living up to expectations, Messi has been the key to Argentina's run to the last 16, scoring four of his team's six goals. There'll likely be more to come from the Barcelona star, who has been decisive in matches in Brazil without dominating the play.
The U.S. has already done well to emerge from a tough group, behind Germany but ahead of Cristiano Ronaldo's Portugal, and should be a match for a talented Belgium lineup.
What to watch on Tuesday:
BELGIUM vs. UNITED STATES
The stakes are high, but still expect the United States to show a more attacking game against Belgium after lacking bite so far in the tournament. The Americans only managed the second-lowest number of attacks out of the 32 teams during the group stage, with just 72.
Speaking after the U.S. lost 1-0 to Germany, U.S. coach Jurgen Klinsmann said: "We will work ... to shift our entire game up forward. So that will put more pressure on the opponents and create more chances."
The good news on the injury front for the U.S. is that forward Jozy Altidore is available after straining his left hamstring in the team's opener against Ghana on June 16. He didn't play the next two group games but should be available to start on the bench on Tuesday.
Belgium's main threat will come from the creative skills of playmaker Eden Hazard, who provided two decisive assists in group stage victories over Russia and Algeria.
Belgium's strikers have so far failed to deliver at the tournament, but the defense has been solid. The question mark at the back, though, is whether captain and central defender Vincent Kompany will be fully fit after a recurring groin strain. He did train on Monday, but could still be a doubtful starter for the match.
Klinsmann created a stir by saying he isn't happy with FIFA's choice of referee, Algeria's Djamel Haimoudi. Algeria was eliminated by the U.S. in 2010, and Algeria played in the same first-round group as Belgium.
Belgium coach Marc Wilmots dismissed Klinsmann's comments, saying: "If we start going into this, it is looking for excuses ahead of the match."
The United States and Belgium haven't played in the World Cup since the first tournament in 1930, a 3-0 win by the Americans.
ARGENTINA vs. SWITZERLAND
Argentina has seemed like a one-man team at this tournament, with Lionel Messi almost single-handedly helping his teammates into the second round. Now that striker Sergio Aguero has been ruled out with a thigh strain, coach Alejandro Sabella is expected to turn to Ezequiel Lavezzi to sharpen the attack and hopefully ease some of the pressure on Messi.
"Everybody said we would score loads of goals in the group stage and it's clear that didn't happen," midfielder Maxi Rodriguez said.
Switzerland knows what to expect, and that it will have to produce its best defensive performance of the tournament.
"I think any defense will face problems when facing Messi, and problems are there to be solved," the team's German coach Ottmar Hitzfeld said on Monday. "How to stop Messi? We will show you tomorrow how we do it."
Bayern Munich's Xherdan Shaqiri, who has earned the nickname "the Alpine Messi", will be driving the Swiss forward. A win would equal Switzerland's biggest football achievement to date -- a place in the quarterfinals in 1954.