The South Australian side were minor premier winners in the inaugural A-League season in 2006 and runners-up to Melbourne Victory in 2007 but missed out on the final series this year after a poor run of one win in 10 games in the closing weeks of the season.

But they took full advantage of their time off to gear up for their second Champions League campaign and it appears to have paid off in a big way with the Reds topping their group before eliminating Japanese champions Kashima Antlers in the quarter-finals.

And the club are now within touching distance of the final and a lucrative spot in the FIFA Club World Cup after a stunning 3-0 win over big-spending Uzbek side Bunyodkor in the first leg of the semi-finals at Hindmarsh Stadium on Wednesday.

"You always start the season wanting to get into the top four of the A-League and qualifying for the play-offs but it probably gave us the opportunity to have a good six weeks of hard preparation," Vidmar told PA Sport.

"We gave the players a few weeks off and then we came back and we worked them extremely hard and we lifted up all the fitness and technical levels and it worked well for us.

"If we had gone into the (A-League) final series then we probably would have had only a couple of weeks of preparation. By not being in the finals, we actually got more time so that actually helped us."

Adelaide failed to make the quarter-finals in their inaugural Champions League campaign but the lessons learnt from that experience were put to good use in their preparations for this year's competition.

"We missed out by five points but we knew there was not much difference between ourselves and the other teams," said the 41-year-old, who had a spell at J.League side Sanfrecce Hiroshima in the late 1990s.

"We lost two games 1-0 and we were leading (Korean league champions) Seongnam 2-0 and drew the game 2-2 so we knew there was not much difference.

"Certainly this year we made the team a lot stronger. There were some small details that we fixed and the players did the work and got the results."

With the A-League in its off-season from March to May, when Adelaide were playing their Champions League group stage matches, warm-up games were set up with fellow qualifiers Melbourne Victory to give the team some much needed match action.

"What we learned in 2007, we implemented in 2008. We knew that the first few games were played every three weeks and then they were played every fortnight so we scheduled (friendly) games against Melbourne Victory in the weeks between those games.

"We tried to make of it as much as we could so it became more of a weekly competition for us and that helped.

"Now it's a little bit different because we play mid-week and then three or four days later, we play in the domestic competition.

"That's very difficult. Obviously it would be more ideal if we had six or seven days to prepare but we don't. It's very different for us because there are only a few players on our team who have gone through that and when you're not used to that, it takes a big toll."