The Dons secured one of their most impressive results in recent years when they won 3-0 in the second qualifying round first-leg tie on the shores of the Adriatic last week – against a side who have made it to the group stages of the competition for the last two seasons.
McInnes has no fresh injury concerns for Thursday’s game; Mark Reynolds (shoulder) remains out of contention after surgery but he is adamant that their is still work to be done.
The Aberdeen manager told The Scotsman: “I can’t emphasis enough how much we have to be on our guard in this game. I was standing beside some Aberdeen supporters who were queuing for tickets at Pittodrie this week.
“They didn’t see me but I overheard one saying the result in Croatia suggested Rijeka aren’t as good as everyone has been making out.
“That sort of attitude and approach could be our undoing. Nobody at Aberdeen can afford to think the job has been done. This will be as tough a game as we have played since I came to Aberdeen.”
McInnes has also warned the Dons faithful not to expect an overly gung-ho approach from his side on Thursday night, despite their healthy advantage from the first leg.
He said: “Domestically we have always tried to show them an Aberdeen side on the front foot but that can’t always happen in European football. I anticipate them maybe doing something a wee bit different so we may need to do the same.”
The winners face a trip to either Kazakhstan or Armenia in the third qualifying round; Kairat of Kazakhstan hold a 3-0 advantage from their first leg against Alashkert, the conquerors of St Johnstone in the first round earlier this month.