With regulars Xu Yunlong, Batella and Guerron on the bench though, Guoan had a dream start with the 20th minute goal by Nigerian forward John Utaka and continued to create havoc in FC Seoul's backyard, but South Korean keeper Kim Yong-Dae cleared all the threats.
Guoan had wasted a few chances in the second half before Kao Yao-Han equalized on a pass by Yun Il-Lok at the 71st minute.
Guoan goalkeeper Yang Zhi was red-carded for bringing down a rival outside the box in the injury time.
In Osaka, Japan, Luneng got an away victory with ease, beating Crezo Osaka 3-1.
Luneng's new signing Aloisio opened the account six minutes into action and Vagner Love scored in 26th and 56th minute.
Osaka pulled one goal back in the last minutes.
Japan's Sanfrecce Hiroshima in Group F shared the same destiny with Osaka, suffering a 2-1 away loss to Central Coast Mariners from Australia.