Buriram United reached the knockout stage of the ACL after a roller coaster evening in Seoul.
The Thunder Castle twice equalized moments after going behind to draw 2-2 with FC Seoul while in Japan, Vegalta Sendai unexpectedly lost 2-1 at home to Jaingsu Sainty to ensure that the Thai side progressed.
FC Seoul made sweeping changes to their side with ten alterations while a depleted Buriram squad could only name four substitutes on their bench.
Despite the wholesale changes, it was the Koreans who made the better start with Kim Hyun Sung and Ko Kwang Min spurning half decent chances for early goals.
The opening period burst into life ten minutes before the interval. Kim Hyun Sung latched onto a layoff to poke straight at Siwaruk while at the other end, Yu Sang Hun had to be alert to block from Adisak after the Buriram man had raced onto a weakly headed backpass.
Four minutes before the break, Hirano was pulled back by Han Tae You on the edge of the box and the referee pointed to the penalty spot. An unconvincing Carmelo Gonzalez stepped up to take the kick and his soft effort was pushed out for a corner by Yu Sang Hun.
The young keeper then denied Adisak again in the last minute of the half by spreading his large frame in front of the Buriram wide man.
FC Seoul tinkered with their formation at the interval and it paid dividends in the 54th minute when Jung Seung Yong slotted home at the back post to finish off a delicious passing move.
Two minutes later, the Thunder Castle roared back when a through ball from Carmelo split the Korean back four. Hirano's timed run beat the offside trap and he touched it to Ekkachai to side foot home.
The hosts retook the lead in the 74th minute with Kim Hyun Sung heading a floated Molina free kick past Siwaruk.
Unbelievably, lightning struck twice as Buriram levelled seconds afterwards for the second time. Theerathorn whipped in a free kick from the right straight through a cluster of bodies into the back of the net.
With the result in the other group game being in Buriram's favour, the objective for Buriram was to shut up shop.
They managed to do that and as the final whistle blew, Buriram players and staff anxiously awaited the final score from Vegalta Sendai.
It did finish 2-1 for Jaingsu Sainty which means that Buriram will now take on Bunyodkor of Uzbekistan in a two legged tie in the Round of 16.