Derek Adams said individual mistakes were the difference between Ross County and Kilmarnock as they went down 2-1 in Dingwall.
Josh Magennis and Tope Obadeyi scored either side of half-time for Killie.
Liam Boyce gave County hope with a late goal, but they could not find an equaliser.
"The two goals were poor from a headed point of view," he said. "You've got to stop the cross, you've got to stop the ball getting to the man in the box."
The result leaves Ross County rooted to the bottom of the table and still looking for their first point of the season.
"We started the game very well, for the first 35 minutes we were on top in the match," Adams told BBC Scotland.
"We've had a lot of chances on goal and I feel we should have been ahead before Kilmarnock got theirs not long before half-time.
"It's a goal we could have stopped.
"Other than that they didn't really cause us too much trouble in the first half.
"From our point of view we scored a good goal from Liam Boyce. It's a good cross from Joe Cardle, but we didn't have the urgency in the last 10-15 minutes to score that second goal.
"You've got to stop the ball getting to the attackers for the headers. These are things individuals have to deal with and we could have done better.
"The positive is that we played well for 35 minutes in the first half and took the game to Kilmarnock. We were in control of the game and looked like the side that were going to score first."