The result appears a blow to former Central Coast Mariners captain John Hutchinson's chances of keeping the job permanently having succeeded Harry Kewell in July,
Albanian winger Jasir Asani hit a hat-trick for the tournament debutants who scored five in the in the second half at the Gwangju World Cup Stadium.
Brazilian Elber scored twice for Marinos who were only 3-2 down after an hour.
The Korean side raced clear with three quick-fire goals in six minutes before Marinos substitute Carlos Eduardo was sent off 12 minutes from time.
Shanghai Shenhua came back from going behind to a fine 53rd minute finish by Brazilian striker Jorge Teixeira to defeat former champions Pohang Steelers 4-1 in Shanghai.
Andre Luis, Cephas Malele (two) and Gao Tianyi scored.
With Shandong Taishan beating Central Coast Mariners 3-1 in Jinan it was a successful evening for Chinese clubs.
Japanese champions Vissel Kobe left Thailand frustrated as Takayuki Yoshida's outfit were held to a 0-0 draw by Buriram United, with Australian international defender Curtis Good clearing a late Daiji Sasaki effort off the line.
In the west Asian side of the draw Saudi Arabia's Al-Hilal cruised to a 3-1 win over Al-Rayyan of Qatar as Jorge Jesus' side made an ominous start to the league phase.
Sergej Milinkovic-Savic, Joao Cancelo and Marcos Leonard scored but it could have been more as Aleksandar Mitrovic's penalty was saved by Paulo Victor and Malcom hit the post for the Saudi Pro League champions.
Al-Wasl of the United Arab Emirates picked up a 1-0 win over Uzbekistan's Pakhtakor in Tashkent.
Al-Nassr's 1-1 draw on Monday against Al-Shorta in Baghdad, following a poor start in the Saudi Pro League, appears to have been the final straw for coach Luis Castro who has been fired by Cristiano Ronaldo's club.
The revamped Asian Champions League Elite has reduced the number of teams from 40 to 24 with the Swiss League system being used in the opening phase.
Twelve teams in both east and west Asia will play eight games in the league phase with the top eight finishers on each side of the continent advancing to the last 16 in March.
