Mehdi Taremi's second-half strike condemned China to a 1-0 defeat to Iran on Tuesday in a major blow to their hopes of qualifying for next year's World Cup.
Marcello Lippi's team raised Chinese hopes by upsetting South Korea last week, but they were unable to overturn Iran's flawless home record in Group A.
While Iran, Asia's top-ranked team, maintain their four-point cushion at the top of the group, China are second from bottom with only three games to go.
Taremi settles it
A tepid first half came alive near the break when Taremi's miskick let China off the hook and Zeng Cheng saved well from both Milad Mohammadi and Masoud Shojaei, who then blazed a bicycle kick over the bar.
After keeping Iran at bay in the first half, China will be cursing themselves for the way they conceded immediately after the resumption, when a howler of a defensive header was directed into the middle of the penalty area.
Shojaei went up for the high ball and the rebound fell to Taremi, who gratefully swept home the chance to put Iran 1-0 ahead and lift the noisy Azadi Stadium crowd.
China looked stunned but they finally gathered themselves with Yu Dabao, who scored in last week's 1-0 win over South Korea, going close with a similar chance at the near post on 64 minutes.
Defender Mei Fang put another header over from a corner on 78 minutes but despite more encouraging signs from China, Russia 2018 again looks remote.