The Foxes lost via a Federico Di Francesco Palermo goal at Chesterfield on Friday night.
Cooper later said: “I thought it was a good pre-season game. I thought our general, in possession play was miles better than what it was against Shrewsbury.
"In certain aspects, it was the best we’ve been so far in pre-season. Where it didn’t hit the levels was the final third. We got into loads of crossing positions and final pass positions, but we weren’t as productive as what we should be and what we need to be.
"When we did get opportunities on goal, we never seemed to get good strikes on the ball, or we mistimed headers. For what we’re going into, that needs to be better. Up until the final third, I thought we were good. In the final third, we need to improve.”