Brazilians Eninho and Luiz Henrique scored to give the 2009 champions a 2-1 win at their home Jeonju World Cup stadium and a 4-2 aggregate victory after they defeated Ulsan by the same margin away on Wednesday.
Spurred on by a crowd of more than 33,000, the home side rallied from 1-0 down after Seol Ki-hyeon had put Ulsan in the lead in the 56th minute.
Eninho equalised three minutes later with a penalty and Luiz burst past two defenders and fired a piledriver into the roof of the net in the 68th minute to take victory for Jeonbuk.
Jeonbuk, who lost to Qatar's Al Sadd on penalties in the Asian Champions League final last month, pocketed 300 million won ($266,000) for the victory.
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