Robben's superb winner in Bayern Munich's 1-0 win over Olympique Lyon in their semi-final first leg gave the watching Japan coach a reality check before this year's World Cup.
"Robben is a really amazing player," Okada told Friday's Sankei Sports newspaper. "I don't know how you stop him. He can come up with incredible goals like that."
Okada's side were easily beaten 3-0 by the Dutch in a friendly last September but the Japan coach refuses to backtrack from his declared target of a World Cup semi-final spot.
Japan also face Cameroon and Denmark in Group E in South Africa and Okada been criticised for placing extra pressure on his players.
"They also have players like (Robin) van Persie and (Dirk) Kuyt," said Okada. "You can't simply man-mark every one of them.
"The Dutch can shoot from any range - totally different to Japan," he added, admitting in public for the first time what his employers and even his players have been saying for months.
"I will need to impress on the players a real sense of urgency. The Dutch really are a high-level team."
