Japan had a late strike from Yosuke Ideguchi to thank for earning a fortuitous 1-0 win over North Korea on Saturday to put Vahid Halilhodzic's side on top of the early standings at the East Asian Championships.
Ideguchi's deflected effort in the 94th minute in front of just over 20,000 fans at Ajinomoto Stadium secured all three points for Japan. They move to the top of the standings after South Korea and China played out a 2-2 draw earlier in the evening.
The North Koreans were unfortunate not to take something from the game, with Japan goalkeeper Kosuke Nakamura pulling off a fine save to deny Kim Yu-sung in the 69th minute. The Kashiwa Reysol custodian threw himself at full stretch to push the 4.25 SC striker's header around the post.
A minute later, Jorn Andersen's side were frustrated again. Pak Myong-Song's shot went over the bar, with the goal at his mercy as Japan's domestic-based line-up lacked a cutting edge throughout.
But, just as the game looked set to end in a scoreless draw, Ideguchi smashed his shot from outside the area. A deflection helped the ball past 2010 World Cup veteran Ri Myong-Guk in the North Korean goal.
"It was a good victory but we were lucky," Halilhodzic said. "Our opponent was well organised and defended well.
"There were many players who were playing their first game for Japan and we were not able to call up many players when we were making this team.
"The other side had a stronger squad so there are several positive factors for us. We never gave up, we never got frustrated. We were patient."
Yu Dabao, meanwhile, made a goal-scoring return to the China national team as Marcello Lippi's side score 14 minutes from time to pick up a 2-2 draw with South Korea in the tournament's opening game.
Wei Shihao had given the Chinese the lead after just nine minutes, scoring his first ever goal for the national team on his debut as Lippi's youthful team made a promising start.
China started with six players aged 22 or under and the South Koreans eventually exploited that inexperience through the physical presence of towering Ulsan Hyundai striker Kim Shin-Wook.
Kim pulled the Koreans level just three minutes after Wei's opener before his cushioned header set Lee Jae-Sung up to score a second for Shin Tae-Yong's side in the 19th minute.
Chinese goalkeeper Yan Junling impressed between the posts to keep the Koreans within striking distance with fine saves either side of hal-time break.
In the 76th minute, Yu claimed the equaliser when he powered through the Korean defence to head home Li Xuepeng's cross from the left.
"I have high expectations of Yu Dabao and he scored today," Lippi said. "He's had a bad year this year, he was injured and his playing time was short.
"However, he had made a contribution to the national team before and he's played a lot of games. He scored twice in a match against South Korea before so I knew what he could do.
"In the second half we changed the strategy and that worked well. We decided to have a more compact defence and we decided to be more focused on that. That worked well. Xiao Zhi is a tall player and his introduction worked positively and as a result we played better."