"They have improved from the last time we played them. There is no doubt it will be a tough match," Okada said as he returned home after seeing group leaders Australia struggle past Uzbekistan 2-0 in Sydney yesterday.
Japan were held to a 1-1 draw by the Uzbeks at home last November and will face them away on 6 June.
"They have new players. In particular, (Farhod) Tadjivev made a strong impression. He is tough and has good technique," Okada said.
The 22-year-old striker scored a hat-trick in a 4-0 win over Qatar at the weekend.
Japan could secure a fourth consecutive berth in the FIFA World Cup finals if they collect three points in their three remaining qualifiers, but Okada said Japan should go all out for three points in the next game. "If you feel complacent, it will prove disastrous," he said.
Commenting on Bolivia's 6-1 upset of Argentina in La Paz Wednesday in the South American qualifying round, Okada said: "As I have always said, you never know what happens in World Cup qualifiers."