Argentinian midfielder Conca was served with a nine-match suspension by the club for his reaction to being substituted against Jeonbuk in the previous round of matches.

But Conca was selected against all expectations and provided the late drama by converting from the spot to send Guangzhou to the top of Group H.

Coach Lee Jang-soo saw his decision to field the former Fluminense player justified, but there were worrying moments for visitors Guangzhou before the penalty came.

They went ahead through Lin Gao after 49 minutes but were pegged back when substitute Suriya Domtaisong levelled for Buriram eight minutes later, and a draw would have seen Guangzhou miss out on a top-two finish.

Conca had the decisive say, though, which left Jeonbuk Motors down in third place after their 2-0 home defeat at the hands of Kashiwa Reysol, who finished second.

Jeonbuk had been top of the table at the start of the sixth and final round of group games, but they fell behind against Kashiwa when Leandro Domingues netted with a fine low shot across goal into the bottom left corner after 48 minutes.

Junya Tanaka added a second goal in the 61st minute, tapping in from close range after Leandro Domingues' shot was touched against the right post.

Koreans Seongnam Chunma made certain of their place in the next round by posting a 3-0 win in Group G over Chinese side Tianjin Taida.

Yoon Bit-Garam gave Seongnam a 33rd-minute lead and Vladimir Jovancic made it 2-0 in the 48th minute before adding a penalty 20 minutes later.