Wenger believes the improvement across Europe means navigating a qualifier is more difficult than ever before.
"Looking at the quality in Europe, it is going up, for any English team it is difficult. I have felt that for a few years now," Wenger said.
"Where it [Champions League qualification from fourth place] was just a formality before, now it is not.
"With Udinese we had two hard games, they are a top team in Serie A."