Battling for a place in the quarter-finals of the 2014 World Cup are the US and Belgium, who arrived as one of the favourites to lift the trophy but have not yet fired on all cylinders.
The Belgians ground out group wins over Algeria, Russia and South Korea but were far from impressive, failing to score in any of those games until the last 20 minutes.
Defender Thomas Vermaelen has not recovered from a hamstring injury and will miss the game while captain Vincent Kompany will undergo a late fitness test.
But coach Marc Wilmots expects playmaker Eden Hazard, another one who has yet to hit full stride, to have a big influence on the game.
"I'm sure that we'll see a massive Hazard performance tomorrow which could prove decisive," he added.
After muscling out Portugal and Ghana for second spot behind Germany in Group G, the United States have grown in confidence and plan to go on the offensive.
"We have no fear at all," US coach Juergen Klinsmann said on Monday. "We feel fresh, we have recovered well after every game so far. We feel we have just started this adventure."
Klinsmann will be able to call on forward Jozy Altidore, who has recovered from a hamstring injury picked up in their group opener.
Date: Tuesday, July 1
Kick-off: 2000 GMT