The Belgians edged the first leg of the qualifying fixture following an error by Tigers goalkeeper Allan McGregor, but Bruce is confident that his players will learn from the experience.
"We have learned the first lesson of what we are playing in Europe, and that is concentration," Sky Sports News quotes him as saying.
"We made a mistake which cost us the game. Our keeper saved a penalty last Saturday against QPR but today he made a mistake and it's an awful way to lose the match.
"We were very comfortable in the game. We had four good chances to score but we didn't and then he made a mistake in the second half, then they got after us much quicker than in the first half."
The return leg takes place at the KC Stadium next Thursday.