Belgium came into the World Cup as the 'dark horses', the team everyone was backing to cause plenty of shocks and leave many big name team embarrassed.
So far they have, kind of, lived up to that billing. They have won all three of their games, and after the Sokratis Papastathopoulos goal for Greece against Costa Rica last night, they are the only team left in the competition not to concede a goal from open play.
But they have been less than inspiring so far - seeing off the likes of Algeria, Russia and South Korea not much of a challenge for a team with this much talent. Their last 16 opponents will prove a much sterner test.
The USA have pleased many with their approach to the tournament. They lost to Germany in their final group game but had already done enough to advance with a win against Ghana and a draw with Portugal.
Belgium will know this is a far bigger challenge then any they have faced so far at the World Cup.
And one man who also believes they are in for a battle is Jose Mourinho. The Chelsea manager telling Yahoo! this week:
"A good thing for the US is the fact that in the group phase they played against two very important teams. They played against Portugal, they played against Germany. So when you get now Belgium, is Belgium a better team than Portugal is Belgium a better team than Germany, no. So the psychological impact that can have on the US team the fact they are going to play against a good team like Belgium, it is not a drama. And that's a very important part of football especially when you go to knockout."
" I think it will be a good game and I would not be surprised with any result."
For Mourinho to say this is interesting - as no fewer than three players in the Belgium team play for him at Chelsea. Thibaut Courtois and Romelu Lukaku are returning from successful loan spells while Eden Hazard is the mercurial star of the Chelsea team.
Perhaps Mourinho is therefore thinking wishfully that his players get back a little earlier than expected this week.