"We didn't compete enough in challenges and the battles and nasty side of the game," was Billy Davies' view after seeing his side crumble in the face of the Foxes first goal at the Walkers Stadium.
Four away defeats in a row have thrown a huge spanner in the works of Forest's promotion hopes and the manager admitted: "We need to look at why we went ten months unbeaten.
"We will have to change things away from home and play a lot tighter."
For the home side, Nigel Pearson was delighted to with a result that keeps alive their hopes of a top-two finish.
"Our fans will enjoy having the local bragging rights but the bottom line is that this was an important game to win because it means we maintain our momentum," he said.