Shinji Okazaki's late winner against Oman took Japan tantalisingly close to the 2014 World Cup Wednesday, as Group A rivals Iraq also struck in the dying minutes to breathe life into their campaign.
Group B is far tighter with Uzbekistan going top on eight points and lead by a point - though second-placed South Korea have a game in hand as they didn't play on Wednesday - after pulling off a sensational 1-0 win in Iran.
Iran are also on seven points while 2022 World Cup hosts Qatar boosted their hopes of reaching the finals for the first time with a 1-0 win over Lebanon in Doha to also move onto seven points.
Japan went ahead early in Muscat through Hiroshi Kiyotake but they were rocked by Ahmed Mubarak's free kick on 77 minutes. However, Okazaki bundled in the decisive goal on 89 minutes to extend Japan's lead in Group B.
The Asian champions went provisionally eight points clear with only three games left, making progression to their fifth consecutive World Cup, in Brazil, an apparent formality.
"I'm pleased I was able to score because I didn't do much else for the whole of the match," said the modest Okazaki.
"We kept chipping away and found a way to win in the end. We weren't in control today so I hope we can dominate to beat Jordan next time."
Japan's Italian coach Alberto Zaccheroni said the Middle Eastern country's intense heat had hampered his players, but he was proud of their refusal to accept a draw.
"We had set ourselves the target of three points here, and I'm happy we accomplished that goal," Zaccheroni said.
"The heat meant we couldn't play the way we're capable of playing. Oman showed a lot of heart but I'm proud of the way my team refused to give in."
In Doha, Iraq's Hammadi Ahmed also left it late against Jordan before he arrowed a left-footed strike home four minutes from time.
The game's only goal was enough to lift the 2007 Asian Cup champions off the foot of an increasingly tight Group B with their first win in five games.
The result brought relief to Iraq coach Zico who had dropped veterans Younus Mahmoud and Nashat Akram from the squad.
In Muscat, Oman looked dangerous on the break and should have taken the lead against Japan after 10 minutes, but Fawzi Bashir blazed over from a promising position.
Stuttgart's Okazaki, who missed Japan's recent friendlies against France and Brazil, saw a couple of half-chances saved by Oman's Wigan Athletic goalkeeper Ali Al Habsi at the other end, before Kiyotake broke the deadlock.
Oman failed to properly deal with Yuto Nagatomo's cross from the left and Nuremburg midfielder Kiyotake seized on the loose ball to slot home from close range.
The goal settled nerves but Oman were unlucky not to be on level terms in the 36th minute, as Al Ajmi headed against the post. Oman came out with renewed purpose after the break and Mubarak nearly levelled it from long range.
Kiyotake and Sakai both had chances to extend Japan's lead as the pace slowed, but with 13 minutes remaining, Mubarak squeezed in a low free kick which sent the home fans into a frenzy.
However as Oman pressed for the winner, substitute Gotoku Sakai raced free on the left flank and his cross was flicked on at the near post by Yasuhito Endo, leaving the arriving Okazaki with the simplest of finishes.
Qatar's victory over Lebanon came courtesy of a stunning individual effort by Uruguayan-born Sebastian Soria, which saw him take the ball from outside the Qatar penalty area, advance with the ball a considerable distance before cracking a 40-yarder into the Lebanese net.
"This was a much needed win for us and thanks to Sebastian we are now alive in the qualifiers," said Qatar coach Paulo Autuori.