South Korea captain Park Ji-sung inspired his team to a 2-0 win in Japan on Monday evening in Saitama and then declared that it was a deserved victory.
The Manchester United man scored a fine opening goal after five minutes and watched from the bench as Park Chu-young added a second in injury time.
It was a fourth straight win for the 2002 World Cup semi-finalists who head to Austria on Tuesday for warm-up matches with Belarus and Spain.
"We're gaining confidence with every match," said Park after the match. "It was a difficult atmosphere but we kept our focus on attacking.
"I told the players to win their one-on-ones," added the 29 year-old. "Maybe Japan has that mentality too but we were the better team today."
Coach Huh Jung-moo was also happy with a good night’s work.
"The players kept calm and never lost their concentration," said Huh..
"There are still areas we can improve on but we can take several plus points from tonight and go to Austria and work towards our opening World Cup game with Greece."
As well as Greece, Korea take on Argentina and Nigeria in South Africa.