Simon Grayson felt that basic defending errors had proved costly to Preston North End in their defeat to Derby County at Deepdale.
The Lilywhites suffered their third successive Championship loss, beaten 2-1 by the Rams.
A first-half double from Chris Martin put Derby in command, the Scotland international finishing off a fine move on the counter-attack to put the visitors ahead in the 23rd minute.
Martin then struck a fine free-kick into the net eight minutes before the interval to stretch the advantage.
North End were better in the second half after the introduction of new signings Stevie May and Eoin Doyle from the bench, with Joe Garner hitting the post with a shot.
They pulled a goal back in stoppage-time through Daniel Johnson, referee Richard Clark having added 12 minutes on after Rams skipper Chris Baird clashed heads with Garner and had to be stretchered to hospital with a neck injury.
Grayson said: “We knew it was going to be a tough game against a side who had spent a lot of money and are one of the favourites for the division.
”But if you don’t do the basics right against anyone, you don’t give yourself the opportunity to win a game.
“We started well but the two goals which Derby scored I thought we could have defended better.
“Derby will look from their point of view as the first goal being a great ball from Johnny Russell and a great take by Chris Martin.
“But I felt we could have stopped it earlier, Tom Clarke could have got tighter to Russell to start with and we didn’t cover round the back when the ball came in.
“In the second half we had a go and thraetened them, Joe Garner hit the inside of the post and their goalkeeper made some good saves.
“DJ got the goal but unfortunately we could not get the breaks for another.”
Grayson started the game with Garner and Will Keane up front in a 3-5-2, waiting until the 55th minute to introduce May and Doyle to the action in a switch to a 4-3-3 formation.
He said: “The lads who came on affected the game which is what you want with substitutes.
“People might ask why I didn’t start with Stevie May and Eoin Doyle.
“They have only been at the club a short time and were not quite up to full speed with their fitness and how we wanted to play.
“That will come and I think they showed when they came on how effective they can be.”