How will Argentina stop Robben?
As Argentina prepare to fight for a place in the World Cup final, there is little doubt as to the identity of the Dutch danger man.
Even a cursory glance at the tapes of Holland's games will tell manager Alejandro Sabella that Arjen Robben represents a grave danger to his hopes of success. The Bayern Munich playmaker must be stopped.
Robben has two great strengths: His ability to move at speed towards the goal and his ability to move at speed towards the ground.
He cannot be allowed to do either tomorrow morning (Singapore time) and that will be an enormous challenge for Argentina's defenders.
Robben has complained bitterly about the attention that has surrounded him during this World Cup for what Americans supporters have called "flopping".
"In recent days there has been a lot of talk about diving," he said. "Actually I'm tired of this b******t."
It's hard to have much sympathy for him, given that his reputation has been won with a long career of chicanery.
Even Jose Mourinho, his old club manager and the master of the dark arts, spoke this week of Robben's unparalleled ability to "win" a free-kick or penalty.
In his defence, however, Robben was noticeably fighting to stay on his feet against Costa Rica in the quarter-finals, despite repeated and increasingly feverish attempts to displace him.
But the damage was done in the second round, when he controversially tumbled over Rafael Marquez's outstretched leg to win a crucial late penalty.
A subsequent admission that he had dived earlier in that match, though an insistence that the penalty was not the result of a dive, did little to lessen his reputation.
Fortunately for Argentina, they have a number of defenders you would think are too experienced and canny to fall for Robben's tricks.
That said, four World Cups of experience weren't enough to save poor Marquez. Nevertheless, Martin Demichelis should be able to resist the temptation to leave a foot hanging out when Robben passes him.
The Manchester City defender was in excellent form against Belgium in their quarter-final and must surely have done enough to preserve his place.
Famously, Demichelis lacks pace, but he is so shrewd that it doesn't take him long to shuffle into position. With Ezequiel Garay, Argentina have a formidable partnership.
With Javier Mascherano in typically doggish mood, there is a lot of protection in the central areas.
The main threat, however, will come from the flanks and Robben is quite capable of shifting to attack the point of least resistance.
Here, Argentina have issues. On one flank, Pablo Zabaleta is as close to an insurance policy as any manager could need. On the other is Marcos Rojo, an excellent fullback, but a young man with a short fuse.
Suspended against Belgium, he may return for Holland if Sabella deems his pace important enough to balance doubts about his temperament.
The last thing he wants is for an early yellow card to inhibit his defender, or an early red card to compromise his team.
Argentina also rely on their fullbacks to provide width to the rest of the team. If Rojo or Zabaleta are caught out of position, Robben could ravage the gaps behind.
Not only does Robben have the speed to roar in on goal, he has also displayed the wisdom to know when to lay the ball off for his teammates. Not for nothing have the Dutch progressed so far through this tournament.
Sabella will know all of this, but will find himself caught in the eternal gap between ambition and caution.
A place in the World Cup final is at stake, but more than that, a chance to humiliate their biggest rivals in their home is at stake. Robben must be shut down or Argentina will pay a heavy price.