The Reds custodian has described his side's achievement as "massive", with United set to host their Round of 16 match against Nagoya Grampus on May 29
Adelaide United goalkeeper Eugene Galekovic believes the Reds have proved many doubters wrong with the AFC Champions League exploits, but warned it is "just the start" of his side's journey in the competition.
United brushed off a disappointing 2011-12 A-League season to finish top of Group E of the ACL, clinching a home Round of 16 final courtesy of a 2-0 win over Gamba Osaka on Wednesday.
The victory crowned a superb group stage for the Reds, in which they picked up crucial wins away to Uzbek champions Bunyodkor and Gamba among their four victories.
Adelaide now face Gamba's J-League rivals Nagoya Grampus at Hindmarsh Stadium on May 29 in a one-off match, with the winners to progress to the quarter finals.
"It's massive. We know how big it is but when you think about it, it's almost only just the start," Galekovic said.
"Now we've got to worry about the Round of 16 and then hopefully the quarters, semis and the final, and I think we can do what we did in 2008 [when the Reds reached the decider, only to be beaten by Gamba].
"I believed we could get through and I think a lot of the boys did. Obviously you get some of the outside people thinking how much we struggled in the A-League and that we would struggle in the ACL, but it happened last time as well. We believed we could do it and now we've done it."