Shanghai SIPG lost for the second consecutive game as Beijing Guoan handed the Chinese Super League leaders a 2-1 defeat on Saturday.
SIPG won their first six games but have picked up just one point from their last three games, and Shandong Luneng could move into first on Sunday if they win against Beijing Renhe.
SIPG looked as if they would bounce back from last week's loss against Changchun Yatai when Elkeson put them in front after 28 minutes, but two goals in the first five minutes of the second half from Piao Cheng and Cedric Bakambu secured all three points for Guoan, who are now two points behind Shandong in third.
"The start of the second half dictated the outcome of the game," SIPG coach Vitor Pereira said. "In the first five minutes, due to our lack of concentration, we lost two goals. Of course, we tried to equalise, but unfortunately, it didn't happen. This is the reality and football is like this sometimes."
SIPG's evening was made worse with the loss of Hulk with what appears to be an injury to his right hamstring, with the influential Brazil international replaced four minutes before the end of the first half.
Shanghai face Kashima Antlers in the first leg of their Asian Champions League round-of-16 clash in Japan on Wednesday and Hulk will undergo a medical assessment on Sunday to determine the extent of the injury.
Bottom side Dalian Yifang, meanwhile, picked up their first win of the season as they defeated seven-time defending champions Guangzhou Evergrande 3-0.
Nyasha Mushekwi put Dalian in front before a Yannick Carrasco penalty doubled the home side's lead two minutes before the break and Wang Jinxian put the result beyond any doubt with three minutes remaining.
The win moves Dalian off the bottom of the table for the first time as they open up a three-point gap over Guizhou Zhicheng, who take on Tianjin Teda on Sunday.
Elsewhere, Tianjin Quanjian eased the pressure on coach Paulo Sousa with a 1-0 win over Chongqing Lifan. There were further difficulties for Manuel Pellegrini's Hebei China Fortune as they lost 1-0 to Henan Jianye, while Guangzhou R&F handed Shanghai Shenhua a 4-2 defeat.