Meanwhile, Iran stayed on course for a Russia 2018 spot after shifting Uzbekistan from the top of Group A on goal difference with a 1-0 victory in Tashkent.
Iran are also the only team in the group not to concede a goal in three matches so far, having beaten Qatar 2-0 followed by a goalless draw with China.
But the torment continued for Qatar as they remained at the bottom after suffering their third straight defeat on Thursday.
The 2022 hosts were done in by Tottenham Hotspur's Son who extended his electric club form with the winning goal in South Korea's 3-2 triumph in Suwon.
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Qatar fought bravely and they took a shock 2-1 lead into the break thanks to Hassan Al-Haydos's penalty and Sebastian Soria's goal at the end of the first half.
But Uli Stielike's men, seeking their 10th World Cup appearance, levelled through Ji Dong-Won before Son, who has scored five for Spurs already this season, curled the winner on 58 minutes.
"This is the first time in two years that we've come back to win," said the German. "This is the victory that is very important for us because it gave us confidence before going to Iran."
Qatar's new coach Jorge Fossati, who replaced the sacked Jose Daniel Carreno only last month, said he was still optimistic after his team scored their first goals of the third qualifying round.
"I'm very optimistic about the qualification," said Fossati, adding that Qatar "confronted one of the top four teams in Asia".
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In Saitama, Japan needed a 95th-minute strike from substitute Hotaru Yamaguchi to down Iraq 2-1 and stay on track in Asia's final qualifying round.
But China were stunned 1-0 at home by war-ravaged Syria as they slipped to fifth in Group A, with only the top two teams reaching Russia and the third-placed side going into a play-off series.
Japan were headed for a morale-sapping draw against Iraq when Yamaguchi smashed a loose ball from a corner through a forest of legs and into the Iraqi goal.
Genki Haraguchi had put the four-time Asian champions ahead with a brilliant flick between his legs before Saad Luaibi nodded Iraq's equaliser after half-time.
In Xian, Syrian forward Mahmoud Al-Mawas's breakaway goal in the 54th minute settled a gritty game which left China stranded on one point from their first three games in Group A.
Seventy-eighth ranked China have ambitions of hosting and even winning a World Cup, but Al-Mawas dented their hopes of reaching the tournament for a second time at Russia 2018.
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The bustling forward latched onto a long ball and prodded his first touch past on-rushing goalkeeper Gu Chao before controlling the bouncing ball into the net.
In Tashkent, Uzbekistan crashed to their first defeat, a 27th minute header from Jalal Hosseini off a Masoud Shojaei free-kick proving decisive in the match.
Uzbekistan couldn't breach the strong Iranian defence, having lost twice AFC Player of the Year Server Djeparov to injury after the first half.
In Abu Dhabi, the UAE bounced back from their loss to Australia to put their campaign back on track with a 3-1 win over Thailand.
Ali Mabkhout was the hero for the hosts with a goal in each half while Ahmed Khalil added the third in injury time to help UAE record their second win of the campaign, including an upset victory over Japan.
Substitute Tana Chanabut gave the Thais some hope with a fine 65th minute goal, but the UAE were far better on the night as they took their points tally to six.
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