Welsh midfielder Paul Seaman opened the scoring after 34 minutes as Waitakere grabbed an unlikely lead.

Daniel Mullen leveled the score five minutes later and a late goal by Travis Dodd sealed the victory for Adelaide.

They will meet Gamba Osaka in the tournament’s quarter-final on Sunday.

Adelaide will be looking to avenge their defeat against the Japanese side in the 2008 AFC Champions League final.

Comeback

Adelaide laid siege to Waitakere’s area from the very beginning and went close to breaking the deadlock more than once.

They were thwarted by Waitakere keeper Richard Gillespie, who pulled off a string of impressive saves.

Seaman gave Waitakere the lead against the run of play, thanks to a dreadful blunder by Adelaide guardian Eugene Galekovic.

Galekovic failed to handle a tame free-kick as Seaman pounced to stab the ball into an empty net.

Waitakere’s lead lasted for just five minutes as Mullen equalized six minutes before the break via a powerful header after being set-up by Paul Reid's corner.

Adelaide skipper Dodd scored the precious winner seven minutes before the final whistle.

He connected with a precise Reid free-kick to head home past Gillespie and help Adelaide overturn the deficit.

Waitakere goal

Adelaide equalizer

Adelaide winner