Alberto Zaccheroni has called on his Japan players to prove themselves by going further than the Asian Cup quarter-finals.A Shinji Okazaki hat-trick and two goals from Ryoichi Maeda accounted for Saudi Arabia in the final Group B match-day in Al-Rayyan on Monday.

The win sets up a quarter-final with Qatar, and Zaccheroni knows his team will need to be on their guard against the much-improved host nation.

"I am very satisfied with this result," Zaccheroni said.

"We have overcome the first obstacle of the AFC Asian Cup, which was to get through the group stage, and we are improving game by game at this tournament."

"I was a little worried about making mistakes but we did not. The players had a great performance."

"In any competition we like to get the good results. Both physically and mentally, if those elements are not good then normally you cannot win the matches."

"Japan is behind others in preparation and we need to catch up to others and prove ourselves in this Asian Cup."

Qatar were ragged in their 2-0 opening loss to Uzbekistan, but recovered to be beat Kuwait and China and may yet prove a tricky obstacle blocking Japan's path to the last four.

"They have come back from their first-match defeat and have the momentum," Zaccheroni said.

"At the same time Japan is in good condition as well so I expect the next game will be a great match."

Saudi Arabia caretaker coach Nasser Al Johar, who took over from the sacked Jose Peseiro after a shock opening defeat to Syria, believes the 2007 finalists were not equipped to mount a challenge in the tournament.

"Our preparation was not as good as it could have been and we did not have the capability to face other national teams at this tournament," Al Johar

"I am a brave man. Whenever I have the responsibility to take charge of the national team I will take it all the way. I don't worry about other people's comments about my work."

"The Saudi national team is very strong. Sometimes we suffer setbacks but always we recover."