The former captain's close range finish in the 40th minute was enough to see off the Japanese outfit as United advanced to the last eight for the second time in their illustrious history.
Adelaide were grateful for Eugene Galekovic, with the goalkeeper making stunning saves off headers from Josh Kennedy and Masukawa Takahiro in either half.
Reds' substitute Sergio van Dijk struck the crossbar with a thumping 25-yard strike while at the other end Jungo Fujimoto saw his free-kick denied by the post - with Galekovic finally beaten.
Uzbek champions Bunyodkor won by the same margin at Seongnam Ilhwa Chunma - winners of the competition in 2010 - to book their spot in the quarter-finals.
Defender Hayrulla Karimov's penalty seven minutes after the interval, following an infringement by Lim Jong-Eun in the area, condemned the South Korea outfit to a narrow defeat.