The Terriers went ahead through Mathias ‘Zanka’ Jorgensen inside four minutes at the King Power Stadium but went on to lose 3-1.
It was Huddersfield’s fourth defeat in half-a-dozen league outings, and life is not about to get any easier with Tottenham Hotspur due at the John Smith’s Stadium on Saturday.
“The players performed to a decent level,” said Wagner, whose side were beaten by goals from Kelechi Iheanacho, James Maddison and Jamie Vardy.
“But we made so many big individual mistakes – and especially before the three goals.
“The first was a poor touch and we conceded a counter from our set play.
“The second we gave away a free-kick in a very dangerous area when we could very easily have cleared the ball and then, for the third one, we produced a missed pass in an area where everyone knows this is not possible against a team like Leicester, because of how they play in behind.
“Jamie Vardy has scored a hundred of these goals, so every single goal we conceded was a present. The opposition didn’t have to invest enough to score against us.
“The players have been in football long enough to know there was something for us in this game. We looked solid for long periods and went in front. We also had clear-cut chances to score when it was still at 1-1.
“We can’t make mistakes like this and expect to get points in the Premier League.”