Tianjin Quanjian handed Guangzhou Evergrande their first defeat in 13 games as Fabio Cannavaro's side notched up a surprise 4-3 win over the reigning Chinese Super League champions on Sunday.
The loss means the lead held by Luiz Felipe Scolari's side at the top of the standings over Shanghai SIPG has been trimmed to just one point as the season hits the halfway stage.
Yu Hanchao gave Guangzhou a half-time lead, but the six-time Chinese champions struggled in the second half as they slipped to only their second defeat of the season.
Sun Ke levelled with a header just a minute after the restart and, five minutes later, last season's Chinese second-tier winners took the lead with another header from Kwon Kyung-Won.
Alexandre Pato struck for Tianjin in the 68th minute only for Paulinho to reduce the deficit to a solitary goal four minutes later.
Wang Yongpo's penalty restored Tianjin's two-goal cushion nine minutes from the end, leaving Paulinho's second strike two minutes into injury time to serve as little more than a late consolation.
"It was a very tight game. Both sides are strong. Tianjin took their chances and won," Scolari said. "Players are not machines, so they will have ups and downs.
"Today our loss was due to our own problems, issues with set pieces and others issues. It's normal. The league is a long campaign and nothing will be decided in just one match. We will get back on track.
"Our points total is good and within my expectation. I want to say being the half-season champion doesn't mean much to me, it's not the real title. The one who's at the top in the end is the champion."
Meanwhile, Yanbian Funde picked up a 2-1 win over Guizhou Zhicheng, with Tian Yinong scoring the winning goal eight minutes from time to drop Fabio Capello's Jiangsu Suning to the bottom of the standings.